In the Philosophy of Mind, Parallelism is a dualist theory of mind-body interaction which maintains that mental and physical events run on a parallel course of existence but do not causally interact with one another.

For example, suppose there are two watches keeping parallel time; just because they move in harmony with one another does not mean one causes the other to do what it does. This view is very similar to Occasionalism which holds that God causes each particular mental event at the time when a physical event happens, except that here God established the parallel courses of mind and body before the actual occurance of either. This is referred to as the preestablished harmony of mind and body, a view popularized by Gottfried Leibniz.