User authentication based on cognitive profiling. First, usage by a person of one or more computerized devices is automatically and continuously tracked. A cognitive profile of the person is automatically and continuously generated based on the tracked usage. Responsive to a request for authenticating an identity of the person, a cognitive question is automatically generated based on the cognitive profile, and is presented to a user professing to be the person. An answer to the cognitive question is received from the user. Finally, the identity of the person is automatically authenticated when the answer to the cognitive question is determined to be correct.