A method for analyzing the pulse‐height distribution of a single NaI crystal gamma ray spectrometer is presented. The method consists in solving the matrix equation,P=KN(hv), forN(hv), the incident gamma ray spectrum in whichPis the pulse‐height distribution, andKis the sensitivity matrix of the detector. A procedure for obtaining the elements ofKfrom curves obtainable from the pulse‐height distributions produced by a few standard monoenergetic sources has been devised. Experimental results are presented which demonstrate the validity of the method.