In some implementations, a user device can schedule tasks based on user behavior. For example, the user device can receive a task request that includes a time window and user/device context parameters for performing the task. The user device can predict a time when the user/device context is optimal for performing the task during the time window based on historical context data. For example, the user device can generate an optimal context score for the task based on the context parameters and the historical context data. The user device can execute the requested task at a current time within the time window when a context score for the current context exceeds a threshold determined based on the optimal context score.