diff --git a/async-ecs/src/access/join.rs b/async-ecs/src/access/join.rs
new file mode 100644
index 0000000..535a3e6
--- /dev/null
+++ b/async-ecs/src/access/join.rs
@@ -0,0 +1,238 @@
+use std::ops::{Deref, DerefMut};
+
+use hibitset::{BitIter, BitSetAll, BitSetLike};
+use log::warn;
+
+use crate::{
+    entity::{Entities, Entity, Index},
+    misc::BitAnd,
+    resource::{Ref, RefMut, Resource},
+};
+
+use super::{read::Read, write::Write};
+
+pub trait Join {
+    type Type;
+    type Value;
+    type Mask: BitSetLike;
+
+    fn open(self) -> (Self::Mask, Self::Value);
+
+    fn get(value: &mut Self::Value, index: Index) -> Self::Type;
+
+    fn join(self) -> JoinIter<Self>
+    where
+        Self: Sized,
+    {
+        JoinIter::new(self)
+    }
+
+    fn maybe(self) -> MaybeJoin<Self>
+    where
+        Self: Sized,
+    {
+        MaybeJoin(self)
+    }
+
+    #[inline]
+    fn is_unconstrained() -> bool {
+        false
+    }
+}
+
+pub struct MaybeJoin<J: Join>(pub J);
+
+impl<T> Join for MaybeJoin<T>
+where
+    T: Join,
+{
+    type Mask = BitSetAll;
+    type Type = Option<<T as Join>::Type>;
+    type Value = (<T as Join>::Mask, <T as Join>::Value);
+
+    fn open(self) -> (Self::Mask, Self::Value) {
+        let (mask, value) = self.0.open();
+
+        (BitSetAll, (mask, value))
+    }
+
+    fn get((mask, value): &mut Self::Value, index: Index) -> Self::Type {
+        if mask.contains(index) {
+            Some(<T as Join>::get(value, index))
+        } else {
+            None
+        }
+    }
+
+    fn is_unconstrained() -> bool {
+        true
+    }
+}
+
+pub struct JoinIter<J: Join> {
+    keys: BitIter<J::Mask>,
+    values: J::Value,
+}
+
+impl<J: Join> JoinIter<J> {
+    pub fn new(j: J) -> Self {
+        if <J as Join>::is_unconstrained() {
+            warn!(
+                "`Join` possibly iterating through all indices, you might've made a join with all `MaybeJoin`s, which is unbounded in length."
+            );
+        }
+
+        let (keys, values) = j.open();
+
+        JoinIter {
+            keys: keys.iter(),
+            values,
+        }
+    }
+
+    pub fn get(&mut self, entity: Entity, entities: &Entities) -> Option<J::Type> {
+        if self.keys.contains(entity.index()) && entities.is_alive(entity) {
+            Some(J::get(&mut self.values, entity.index()))
+        } else {
+            None
+        }
+    }
+}
+
+impl<J: Join> std::iter::Iterator for JoinIter<J> {
+    type Item = J::Type;
+
+    fn next(&mut self) -> Option<J::Type> {
+        self.keys.next().map(|idx| J::get(&mut self.values, idx))
+    }
+}
+
+impl<J: Join> Clone for JoinIter<J>
+where
+    J::Mask: Clone,
+    J::Value: Clone,
+{
+    fn clone(&self) -> Self {
+        Self {
+            keys: self.keys.clone(),
+            values: self.values.clone(),
+        }
+    }
+}
+
+macro_rules! define_tuple_join {
+    ($($from:ident),*) => {
+        impl<$($from,)*> Join for ($($from),*,)
+            where $($from: Join),*,
+                  ($(<$from as Join>::Mask,)*): BitAnd,
+        {
+            type Type = ($($from::Type),*,);
+            type Value = ($($from::Value),*,);
+            type Mask = <($($from::Mask,)*) as BitAnd>::Value;
+
+            #[allow(non_snake_case)]
+            fn open(self) -> (Self::Mask, Self::Value) {
+                let ($($from,)*) = self;
+                let ($($from,)*) = ($($from.open(),)*);
+
+                (
+                    ($($from.0),*,).and(),
+                    ($($from.1),*,)
+                )
+            }
+
+            #[allow(non_snake_case)]
+            fn get(v: &mut Self::Value, i: Index) -> Self::Type {
+                let &mut ($(ref mut $from,)*) = v;
+
+                ($($from::get($from, i),)*)
+            }
+
+            #[inline]
+            fn is_unconstrained() -> bool {
+                let mut unconstrained = true;
+
+                $( unconstrained = unconstrained && $from::is_unconstrained(); )*
+
+                unconstrained
+            }
+        }
+    }
+}
+
+define_tuple_join! { A }
+define_tuple_join! { A, B }
+define_tuple_join! { A, B, C }
+define_tuple_join! { A, B, C, D }
+define_tuple_join! { A, B, C, D, E }
+define_tuple_join! { A, B, C, D, E, F }
+define_tuple_join! { A, B, C, D, E, F, G }
+define_tuple_join! { A, B, C, D, E, F, G, H }
+define_tuple_join! { A, B, C, D, E, F, G, H, I }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J, K }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J, K, L }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J, K, L, M }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J, K, L, M, N }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J, K, L, M, N, O }
+define_tuple_join! { A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P }
+
+macro_rules! define_mutable_join {
+    ($ty:ty) => {
+        impl<'a, 'b, T> Join for &'a mut $ty
+        where
+            &'a mut T: Join,
+            T: Resource,
+        {
+            type Type = <&'a mut T as Join>::Type;
+            type Value = <&'a mut T as Join>::Value;
+            type Mask = <&'a mut T as Join>::Mask;
+
+            fn open(self) -> (Self::Mask, Self::Value) {
+                self.deref_mut().open()
+            }
+
+            fn get(v: &mut Self::Value, i: Index) -> Self::Type {
+                <&'a mut T as Join>::get(v, i)
+            }
+
+            #[inline]
+            fn is_unconstrained() -> bool {
+                <&'a mut T as Join>::is_unconstrained()
+            }
+        }
+    };
+}
+
+define_mutable_join!(Write<'b, T>);
+define_mutable_join!(RefMut<'b, T>);
+
+macro_rules! define_immutable_join {
+    ($ty:ty) => {
+        impl<'a, 'b, T> Join for &'a $ty
+        where
+            &'a T: Join,
+            T: Resource,
+        {
+            type Type = <&'a T as Join>::Type;
+            type Value = <&'a T as Join>::Value;
+            type Mask = <&'a T as Join>::Mask;
+
+            fn open(self) -> (Self::Mask, Self::Value) {
+                self.deref().open()
+            }
+
+            fn get(v: &mut Self::Value, i: Index) -> Self::Type {
+                <&'a T as Join>::get(v, i)
+            }
+
+            #[inline]
+            fn is_unconstrained() -> bool {
+                <&'a T as Join>::is_unconstrained()
+            }
+        }
+    };
+}
+
+define_immutable_join!(Read<'b, T>);
+define_immutable_join!(Ref<'b, T>);
diff --git a/async-ecs/src/access/mod.rs b/async-ecs/src/access/mod.rs
index 1eb7463..65c5d6b 100644
--- a/async-ecs/src/access/mod.rs
+++ b/async-ecs/src/access/mod.rs
@@ -1,10 +1,12 @@
 pub mod accessor;
+pub mod join;
 pub mod read;
 pub mod read_storage;
 pub mod write;
 pub mod write_storage;
 
 pub use accessor::{Accessor, AccessorCow, AccessorType, StaticAccessor};
+pub use join::Join;
 pub use read::Read;
 pub use read_storage::ReadStorage;
 pub use write::Write;
diff --git a/async-ecs/src/dispatcher/task.rs b/async-ecs/src/dispatcher/task.rs
index 3761dd7..fd3fd66 100644
--- a/async-ecs/src/dispatcher/task.rs
+++ b/async-ecs/src/dispatcher/task.rs
@@ -11,13 +11,12 @@ pub async fn execute(
 ) {
     info!("System started: {}", &name);
 
-    run(&name, dispatchable, sender, receivers, world).await;
+    run(dispatchable, sender, receivers, world).await;
 
     info!("System finished: {}", &name);
 }
 
 async fn run(
-    name: &str,
     mut dispatchable: BoxedDispatchable,
     sender: Sender,
     mut receivers: Vec<Receiver>,
@@ -31,8 +30,6 @@ async fn run(
             }
         }
 
-        info!("Run system: {}", &name);
-
         let world = world.borrow();
         let world = world.as_ref().unwrap();
 
diff --git a/async-ecs/src/lib.rs b/async-ecs/src/lib.rs
index 6c088a9..4af94a8 100644
--- a/async-ecs/src/lib.rs
+++ b/async-ecs/src/lib.rs
@@ -11,7 +11,7 @@ pub mod storage;
 pub mod system;
 pub mod world;
 
-pub use access::{ReadStorage, WriteStorage};
+pub use access::{Join, ReadStorage, WriteStorage};
 pub use dispatcher::Dispatcher;
 pub use resource::Resources;
 pub use storage::VecStorage;
diff --git a/async-ecs/src/main.rs b/async-ecs/src/main.rs
index 023f935..986d8ba 100644
--- a/async-ecs/src/main.rs
+++ b/async-ecs/src/main.rs
@@ -2,7 +2,7 @@ use std::io::Error as IoError;
 use std::time::{Duration, Instant};
 
 use async_ecs::{
-    dispatcher::Error as DispatcherError, Dispatcher, ReadStorage, System, VecStorage, World,
+    dispatcher::Error as DispatcherError, Dispatcher, Join, ReadStorage, System, VecStorage, World,
     WriteStorage,
 };
 use async_ecs_derive::Component;
@@ -137,9 +137,11 @@ impl Acceleration {
 impl<'a> System<'a> for Move {
     type SystemData = (WriteStorage<'a, Position>, ReadStorage<'a, Velocity>);
 
-    fn run(&mut self, (position, velocity): Self::SystemData) {
-        let _position = position;
-        let _velocity = velocity;
+    fn run(&mut self, (mut position, velocity): Self::SystemData) {
+        for (position, velocity) in (&mut position, &velocity).join() {
+            position.x += velocity.x;
+            position.y += velocity.y;
+        }
 
         /*
         use specs::{prelude::ParallelIterator, ParJoin};
@@ -157,9 +159,11 @@ impl<'a> System<'a> for Move {
 impl<'a> System<'a> for Accelerate {
     type SystemData = (WriteStorage<'a, Velocity>, ReadStorage<'a, Acceleration>);
 
-    fn run(&mut self, (velocity, acceleration): Self::SystemData) {
-        let _velocity = velocity;
-        let _acceleration = acceleration;
+    fn run(&mut self, (mut velocity, acceleration): Self::SystemData) {
+        for (velocity, acceleration) in (&mut velocity, &acceleration).join() {
+            velocity.x += acceleration.x;
+            velocity.y += acceleration.y;
+        }
 
         /*
         use specs::{prelude::ParallelIterator, ParJoin};
diff --git a/async-ecs/src/misc/bit_and.rs b/async-ecs/src/misc/bit_and.rs
new file mode 100644
index 0000000..1d20964
--- /dev/null
+++ b/async-ecs/src/misc/bit_and.rs
@@ -0,0 +1,55 @@
+use hibitset::{BitSetAnd, BitSetLike};
+
+use crate::misc::Split;
+
+pub trait BitAnd {
+    type Value: BitSetLike;
+
+    fn and(self) -> Self::Value;
+}
+
+impl<A> BitAnd for (A,)
+where
+    A: BitSetLike,
+{
+    type Value = A;
+
+    fn and(self) -> Self::Value {
+        self.0
+    }
+}
+
+macro_rules! bitset_and {
+    ($($from:ident),*) => {
+        impl<$($from),*> BitAnd for ($($from),*)
+            where $($from: BitSetLike),*
+        {
+            type Value = BitSetAnd<
+                <<Self as Split>::Left as BitAnd>::Value,
+                <<Self as Split>::Right as BitAnd>::Value
+            >;
+
+            fn and(self) -> Self::Value {
+                let (l, r) = self.split();
+
+                BitSetAnd(l.and(), r.and())
+            }
+        }
+    }
+}
+
+bitset_and! { A, B }
+bitset_and! { A, B, C }
+bitset_and! { A, B, C, D }
+bitset_and! { A, B, C, D, E }
+bitset_and! { A, B, C, D, E, F }
+bitset_and! { A, B, C, D, E, F, G }
+bitset_and! { A, B, C, D, E, F, G, H }
+bitset_and! { A, B, C, D, E, F, G, H, I }
+bitset_and! { A, B, C, D, E, F, G, H, I, J }
+bitset_and! { A, B, C, D, E, F, G, H, I, J, K }
+bitset_and! { A, B, C, D, E, F, G, H, I, J, K, L }
+bitset_and! { A, B, C, D, E, F, G, H, I, J, K, L, M }
+bitset_and! { A, B, C, D, E, F, G, H, I, J, K, L, M, N }
+bitset_and! { A, B, C, D, E, F, G, H, I, J, K, L, M, N, O }
+bitset_and! { A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P }
diff --git a/async-ecs/src/misc/mod.rs b/async-ecs/src/misc/mod.rs
index 5df1510..061f3c2 100644
--- a/async-ecs/src/misc/mod.rs
+++ b/async-ecs/src/misc/mod.rs
@@ -1,3 +1,7 @@
+pub mod bit_and;
+pub mod split;
 pub mod try_default;
 
+pub use bit_and::BitAnd;
+pub use split::Split;
 pub use try_default::TryDefault;
diff --git a/async-ecs/src/misc/split.rs b/async-ecs/src/misc/split.rs
new file mode 100644
index 0000000..dc05a20
--- /dev/null
+++ b/async-ecs/src/misc/split.rs
@@ -0,0 +1,47 @@
+pub trait Split {
+    type Left;
+    type Right;
+
+    fn split(self) -> (Self::Left, Self::Right);
+}
+
+macro_rules! for_each_prefix (
+    ($m:ident, [$(($acc:tt),)*], []) => {
+        $m!($($acc,)*);
+    };
+    ($m:ident, [$(($acc:tt),)*], [($arg0:tt), $(($arg:tt),)*]) => {
+        $m!($($acc,)*);
+        for_each_prefix!($m, [$(($acc),)* ($arg0),], [$(($arg),)*]);
+    };
+);
+
+macro_rules! split_impl (
+    ($(($a:ident, $b:ident),)*) => (
+        impl<$($a,)* $($b,)*> Split for ($($a,)* $($b,)*) {
+            type Left = ($($a,)*);
+            type Right = ($($b,)*);
+            #[allow(non_snake_case)]
+            fn split(self) -> (Self::Left, Self::Right) {
+                match self {
+                    ($($a,)* $($b,)*) => (($($a,)*), ($($b,)*))
+                }
+            }
+        }
+        impl<$($a,)* $($b,)* TLast> Split for ($($a,)* $($b,)* TLast,) {
+            type Left = ($($a,)*);
+            type Right = ($($b,)* TLast,);
+            #[allow(non_snake_case)]
+            fn split(self) -> (Self::Left, Self::Right) {
+                match self {
+                    ($($a,)* $($b,)* t_last,) => (($($a,)*), ($($b,)* t_last,))
+                }
+            }
+        }
+    );
+);
+
+for_each_prefix! {
+    split_impl,
+    [],
+    [((T0, T1)), ((T2, T3)), ((T4, T5)), ((T6, T7)), ((T8, T9)), ((T10, T11)), ((T12, T13)), ((T14, T15)),]
+}
diff --git a/async-ecs/src/storage/masked_storage.rs b/async-ecs/src/storage/masked_storage.rs
index f2df91e..2328aed 100644
--- a/async-ecs/src/storage/masked_storage.rs
+++ b/async-ecs/src/storage/masked_storage.rs
@@ -5,8 +5,8 @@ use hibitset::BitSet;
 use crate::{component::Component, entity::Entity, storage::Storage};
 
 pub struct MaskedStorage<T: Component> {
-    mask: BitSet,
-    inner: T::Storage,
+    pub(crate) mask: BitSet,
+    pub(crate) inner: T::Storage,
 }
 
 impl<T: Component> MaskedStorage<T> {
@@ -17,6 +17,10 @@ impl<T: Component> MaskedStorage<T> {
         }
     }
 
+    pub fn open_mut(&mut self) -> (&BitSet, &mut T::Storage) {
+        (&self.mask, &mut self.inner)
+    }
+
     pub fn insert(&mut self, entity: Entity, mut component: T) -> Option<T> {
         let index = entity.index();
 
diff --git a/async-ecs/src/storage/storage_wrapper.rs b/async-ecs/src/storage/storage_wrapper.rs
index 322b18f..807121d 100644
--- a/async-ecs/src/storage/storage_wrapper.rs
+++ b/async-ecs/src/storage/storage_wrapper.rs
@@ -1,20 +1,27 @@
 use std::marker::PhantomData;
-use std::ops::DerefMut;
+use std::ops::{Deref, DerefMut, Not};
+
+use hibitset::{BitSet, BitSetNot};
 
 use crate::{
+    access::Join,
     component::Component,
-    entity::{Entities, Entity},
+    entity::{Entities, Entity, Index},
     error::Error,
     resource::Ref,
     storage::MaskedStorage,
 };
 
+use super::Storage;
+
 pub struct StorageWrapper<'a, T, D> {
     data: D,
     entities: Ref<'a, Entities>,
     phantom: PhantomData<T>,
 }
 
+pub struct AntiStorage<'a>(pub &'a BitSet);
+
 impl<'a, T, D> StorageWrapper<'a, T, D> {
     pub fn new(data: D, entities: Ref<'a, Entities>) -> Self {
         Self {
@@ -37,4 +44,71 @@ where
 
         Ok(self.data.insert(entity, component))
     }
+
+    pub fn not(&self) -> AntiStorage<'_> {
+        AntiStorage(&self.data.mask)
+    }
+}
+
+impl<'a, 'e, T, D> Not for &'a StorageWrapper<'e, T, D>
+where
+    T: Component,
+    D: Deref<Target = MaskedStorage<T>>,
+{
+    type Output = AntiStorage<'a>;
+
+    fn not(self) -> Self::Output {
+        AntiStorage(&self.data.mask)
+    }
+}
+
+impl<'a, 'e, T, D> Join for &'a StorageWrapper<'e, T, D>
+where
+    T: Component,
+    D: Deref<Target = MaskedStorage<T>>,
+{
+    type Mask = &'a BitSet;
+    type Type = &'a T;
+    type Value = &'a T::Storage;
+
+    fn open(self) -> (Self::Mask, Self::Value) {
+        (&self.data.mask, &self.data.inner)
+    }
+
+    fn get(v: &mut Self::Value, i: Index) -> &'a T {
+        v.get(i)
+    }
+}
+
+impl<'a, 'e, T, D> Join for &'a mut StorageWrapper<'e, T, D>
+where
+    T: Component,
+    D: DerefMut<Target = MaskedStorage<T>>,
+{
+    type Mask = &'a BitSet;
+    type Type = &'a mut T;
+    type Value = &'a mut T::Storage;
+
+    fn open(self) -> (Self::Mask, Self::Value) {
+        self.data.open_mut()
+    }
+
+    fn get(v: &mut Self::Value, i: Index) -> &'a mut T {
+        // HACK
+        let value: *mut Self::Value = v as *mut Self::Value;
+
+        unsafe { (*value).get_mut(i) }
+    }
+}
+
+impl<'a> Join for AntiStorage<'a> {
+    type Mask = BitSetNot<&'a BitSet>;
+    type Type = ();
+    type Value = ();
+
+    fn open(self) -> (Self::Mask, ()) {
+        (BitSetNot(self.0), ())
+    }
+
+    fn get(_: &mut (), _: Index) {}
 }