The Master of Philosophy (M.Phil. or MPhil, sometimes Ph.M.) is an advanced postgraduate research degree.
The prerequisites required for a Master of Philosophy degree make it the most advanced research degree before the Doctor of Philosophy (Ph.D. or D.Phil.). An M.Phil. is in most cases thesis-only, and is regarded as a senior or second master's degree, standing between a taught Master's and a Ph.D. An M.Phil. may be awarded to graduate students, after completing several years of original research but before the defence of a dissertation, and can serve as a provisional enrollment for a Ph.D.
Although most American universities do not award the M.Phil., a few award it under certain circumstances. At those institutions (most notably Yale University, Columbia University, and more recently the CUNY Graduate Center), the degree is awarded to Ph.D. candidates when they complete their required coursework and qualifying examinations prior to the completion and defense of a doctoral dissertation. This recognizes achievement beyond the Master of Arts and Master of Science degrees conferred after 1–3 years of graduate study and formalizes the more colloquial "All But Dissertation" status; as such, defense of a dissertation proposal is sometimes required for conferral.