diff --git a/widget_state/basic_state.py b/widget_state/basic_state.py
index ff41bdc..9d6143c 100644
--- a/widget_state/basic_state.py
+++ b/widget_state/basic_state.py
@@ -6,14 +6,16 @@
 from __future__ import annotations
 
 from collections.abc import Iterable
-from typing import Any, Callable, Optional
+from typing import Any, Callable, Generic, Optional, TypeVar
 
 from .state import State
 from .list_state import ListState
 from .types import Serializable
 
+T = TypeVar("T")
+R = TypeVar("R")
 
-class BasicState(State):
+class BasicState(State, Generic[T]):
     """
     A basic state contains a single value.
 
@@ -22,7 +24,7 @@ class BasicState(State):
     if the value changed on reassignment.
     """
 
-    def __init__(self, value: Any, verify_change: bool = True) -> None:
+    def __init__(self, value: T, verify_change: bool = True) -> None:
         """
         Initialize a basic state:
 
@@ -39,7 +41,7 @@ def __init__(self, value: Any, verify_change: bool = True) -> None:
 
         self.value = value
 
-    def __setattr__(self, name: str, new_value: Any) -> None:
+    def __setattr__(self, name: str, new_value: T) -> None:
         # ignore private attributes (begin with an underscore)
         if name[0] == "_":
             super().__setattr__(name, new_value)
@@ -63,7 +65,7 @@ def __setattr__(self, name: str, new_value: Any) -> None:
         # notify that the value changed
         self.notify_change()
 
-    def set(self, value: Any) -> None:
+    def set(self, value: T) -> None:
         """
         Simple function for the assignment of the value.
 
@@ -79,7 +81,7 @@ def set(self, value: Any) -> None:
     def depends_on(
         self,
         states: Iterable[State],
-        compute_value: Callable[[], Any],
+        compute_value: Callable[[], T],
         element_wise: bool = False,
     ) -> None:
         """
@@ -109,8 +111,8 @@ def depends_on(
         self.set(compute_value())
 
     def transform(
-        self, self_to_other: Callable[[BasicState], BasicState]
-    ) -> BasicState:
+        self, self_to_other: Callable[[BasicState[T]], BasicState[R]]
+    ) -> BasicState[R]:
         """
         Transform this state into another state.
 
@@ -141,11 +143,11 @@ def __repr__(self) -> str:
     def serialize(self) -> Serializable:
         raise NotImplementedError("Unable to serialize abstract basic state")
 
-    def deserialize(self, _dict: Serializable):
+    def deserialize(self, _dict: Serializable) -> None:
         raise NotImplementedError("Unable to deserialize abstract basic state")
 
 
-class IntState(BasicState):
+class IntState(BasicState[int]):
     """
     Implementation of the `BasicState` for an int.
     """
@@ -158,7 +160,7 @@ def serialize(self) -> int:
         return self.value
 
 
-class FloatState(BasicState):
+class FloatState(BasicState[float]):
     """
     Implementation of the `BasicState` for a float.
 
@@ -182,7 +184,7 @@ def serialize(self) -> float:
         return self.value
 
 
-class StringState(BasicState):
+class StringState(BasicState[str]):
     """
     Implementation of the `BasicState` for a string.
     """
@@ -198,7 +200,7 @@ def __repr__(self) -> str:
         return f'{type(self).__name__}[value="{self.value}"]'
 
 
-class BoolState(BasicState):
+class BoolState(BasicState[bool]):
     """
     Implementation of the `BasicState` for a bool.
     """
@@ -211,7 +213,7 @@ def serialize(self) -> bool:
         return self.value
 
 
-class ObjectState(BasicState):
+class ObjectState(BasicState[Any]):
     """
     Implementation of the `BasicState` for objects.
 
diff --git a/widget_state/dict_state.py b/widget_state/dict_state.py
index e11bdc2..855bf8f 100644
--- a/widget_state/dict_state.py
+++ b/widget_state/dict_state.py
@@ -27,7 +27,7 @@ def __init__(self) -> None:
         super().__init__()
         self._labels: list[str] = []
 
-    def __setattr__(self, name: str, new_value: Any | BasicState) -> None:
+    def __setattr__(self, name: str, new_value: Any | BasicState[Any]) -> None:
         super().__setattr__(name, new_value)
 
         if name[0] == "_":
@@ -36,12 +36,12 @@ def __setattr__(self, name: str, new_value: Any | BasicState) -> None:
         if name not in self._labels:
             self._labels.append(name)
 
-    def __getitem__(self, i: int) -> BasicState:
+    def __getitem__(self, i: int) -> BasicState[Any]:
         item = self.__getattribute__(self._labels[i])
         assert isinstance(item, BasicState)
         return item
 
-    def __iter__(self) -> Iterator[BasicState]:
+    def __iter__(self) -> Iterator[BasicState[Any]]:
         return iter(map(self.__getattribute__, self._labels))
 
     def __len__(self) -> int:
@@ -53,7 +53,7 @@ def values(self) -> list[Any]:
         """
         return [attr.value for attr in self]
 
-    def set(self, *args: BasicState | Primitive) -> None:
+    def set(self, *args: BasicState[Any] | Primitive) -> None:
         """
         Reassign all internal basic state values and only
         trigger a notification afterwards.
@@ -62,4 +62,4 @@ def set(self, *args: BasicState | Primitive) -> None:
 
         with self:
             for i, arg in enumerate(args):
-                self[i].value = arg
+                self[i].value = arg.value if isinstance(arg, BasicState) else arg
diff --git a/widget_state/list_state.py b/widget_state/list_state.py
index d785501..f5f950c 100644
--- a/widget_state/list_state.py
+++ b/widget_state/list_state.py
@@ -7,7 +7,7 @@
 
 from collections.abc import Iterator
 import typing
-from typing import Any, Callable, Optional, Union
+from typing import Any, Callable, Generic, Optional, TypeVar, Union
 
 from .state import State
 from .types import Serializable
@@ -15,13 +15,14 @@
 if typing.TYPE_CHECKING:
     from _typeshed import SupportsDunderLT, SupportsDunderGT
 
+T = TypeVar("T", bound=State)
 
 class _ElementObserver:
     """
     Utility class that keeps track of all callbacks observing element-wise changes of a list state.
     """
 
-    def __init__(self, list_state: ListState) -> None:
+    def __init__(self, list_state: ListState[T]) -> None:
         """
         Initialize an `_ElementObserver`.
 
@@ -38,12 +39,12 @@ def __call__(self, state: State) -> None:
             cb(self._list_state)
 
 
-class ListState(State):
+class ListState(State, Generic[T]):
     """
     A list of states.
     """
 
-    def __init__(self, _list: Optional[list[State]] = None) -> None:
+    def __init__(self, _list: Optional[list[T]] = None) -> None:
         """
         Initial a `ListState`.
 
@@ -56,7 +57,7 @@ def __init__(self, _list: Optional[list[State]] = None) -> None:
 
         self._elem_obs = _ElementObserver(self)
 
-        self._list: list[State] = []
+        self._list: list[T] = []
         self.extend(_list if _list is not None else [])
 
     def on_change(
@@ -82,7 +83,7 @@ def remove_callback(
         if cb in self._elem_obs._callbacks:
             self._elem_obs._callbacks.remove(cb)
 
-    def append(self, elem: State) -> None:
+    def append(self, elem: T) -> None:
         """
         Append a `State` to the list and notify.
 
@@ -110,7 +111,7 @@ def clear(self) -> None:
 
         self.notify_change()
 
-    def extend(self, _list: list[State]) -> None:
+    def extend(self, _list: list[T]) -> None:
         """
         Extend the list and notify.
 
@@ -124,7 +125,7 @@ def extend(self, _list: list[State]) -> None:
             for elem in _list:
                 self.append(elem)
 
-    def insert(self, index: int, elem: State) -> None:
+    def insert(self, index: int, elem: T) -> None:
         """
         Insert an element at `index` into the list and notify.
 
@@ -165,7 +166,7 @@ def pop(self, index: int = -1) -> State:
 
         return elem
 
-    def remove(self, elem: State) -> None:
+    def remove(self, elem: T) -> None:
         """
         Remove an element from the list and notify.
 
@@ -189,7 +190,7 @@ def reverse(self) -> None:
         self.notify_change()
 
     def sort(
-        self, key: Callable[[State], SupportsDunderLT[Any] | SupportsDunderGT[Any]]
+        self, key: Callable[[T], SupportsDunderLT[Any] | SupportsDunderGT[Any]]
     ) -> None:
         """
         Wrapper to the sort method of the internal list.
@@ -205,10 +206,10 @@ def sort(
         self._list.sort(key=key)
         self.notify_change()
 
-    def __getitem__(self, i: int) -> State:
+    def __getitem__(self, i: int) -> T:
         return self._list[i]
 
-    def index(self, elem: State) -> int:
+    def index(self, elem: T) -> int:
         """
         Wrapper to the index method of the internal list.
 
@@ -223,7 +224,7 @@ def index(self, elem: State) -> int:
         """
         return self._list.index(elem)
 
-    def __iter__(self) -> Iterator[State]:
+    def __iter__(self) -> Iterator[T]:
         return iter(self._list)
 
     def __len__(self) -> int:
diff --git a/widget_state/util.py b/widget_state/util.py
index 7f26660..4dd7b08 100644
--- a/widget_state/util.py
+++ b/widget_state/util.py
@@ -12,7 +12,7 @@
 from .basic_state import BasicState
 from .state import State
 
-T = TypeVar("T", bound=BasicState)
+T = TypeVar("T", bound=BasicState[Any])
 P = ParamSpec("P")