Many patients suffering from schizophrenia feel dispossessed from some of their actions or thoughts. This dispossession could result from impaired self-monitoring (SM), defined as the ability to monitor self-willed intentions and actions. SM has been widely studied during the past decades with very different paradigms; central error correction, feedback distortion, sense of effort, and motor imagery. The present article first reviews the methods used and results obtained in investigation of SM. Second, we address what we consider to be the critical questions that must be answered in order to fully understand the role of SM deficit in schizophrenia: 1) Is SM deficit only impaired in patients with specific symptoms? 2) Is SM deficit associated with other cognitive processes that are also impaired in patients with schizophrenia? 3) Can SM impairment be characterized as a trait or a state marker? Finally, we discuss the consequences of SM investigation on diagnostic evaluation and therapeutic orientations and we propose future research that we think is essential in order to clarify the role of SM in schizophrenia.