"Thought insertion" is one of Kurt Schneider's first rank symptoms of schizophrenia. Earlier, Karl Jaspers had made a finer distinction, differentiating between "thought insertion in a narrower sense" and "made thoughts." However, most German and English writers have dispensed with the Jasperian criteria for this differentiation and consequently their use of the term "thought insertion" is broader. Such authors, including Kurt Schneider and Weitbrecht, usually speak of "thought insertion", "made thoughts", and "influencing of thoughts" as if they were identical phenomena. In contrast, Jaspers' differentiation offers us the possibility of more clearly distinguishing such symptoms and thus his distinction should not be neglected. Furthermore, the Jasperian criteria can be logically and usefully extended to all "made and passivity experiences" enabling one to recognise four aspects of such phenomena. Some general differential diagnostic considerations with respect to "thought insertion" are then presented.