There could be various reasons for your `setState` not working as expected. Here are few things to check: 1. **Asynchronous nature of `setState`**: The `setState` method is asynchronous. This means that state updates may not happen immediately, and if you try to access the state value immediately after calling `setState`, you might get the old value. If you would like to perform an action right after the state has been updated, you can pass a callback function as the second argument to `setState`. 2. **Incorrectly mutating state**: React state should not be mutated directly. For example, if your state is an object or an array, you should create a new object or array with the updated properties instead of directly changing the properties of the existing object or array in the state. 3. **Incorrect use of `this`**: If you're using a regular function to define your method that calls `setState`, the value of `this` may not be what you expect. To ensure `this` refers to the component instance, you can either bind the method in the constructor or define your method as an arrow function. 4. **Component not re-rendering**: If state changes but the render method’s output remains the same, React may short-circuit the re-rendering process and skip updating the DOM. Remember, it would also help us provide a more accurate solution if you can include a snippet of your code.