The present study is the continuation of an extensive investigation aimed at the development of rational design rules for formed pressure vessel heads.The program was sponsored and coordinated by the Pressure Vessel Research Committee.This problem was one of the first research projects the Design Division of PVRC selected for study and by maintaining its interest stimulated an increasing amount of work on the diverse behavior of seemingly similar head shapes.In the course of this work, not only new analysis techniques were developed but also a number of new failure modes unique to these deceivingly simple looking geometrical shapes were uncovered.Many of the details of the problem have been studied, and while much remains to be done, enough data became available to assemble a consistent set of design rules for the more common dished heads.This report is an attempt to summarize the present state-of-the-art and to provide the background information for the recommended changes in the present design rules.