Voluntary health insurance plans have grown during the past two decades from humble beginnings. While the growth has been progressively forward, at times it has been erratic. In some instances plans were started by persons who, while well meaning, knew little about insurance. In most instances, however, expert advice has guided the development of the various plans and, as experience was gained, more effective organization, planning and coverage were provided. In various ways such improvement is obtained. For example, the recent publication of an actuarial and statistical manual by the Blue Cross Commission and the Blue Shield Commission, replete with punch card forms and coding instructions for the many types of illnesses which result in claims, marks a significant step forward. Some of the older plans, however, have well established statistical procedures. Although this manual has not yet been put into operation by all Blue Cross and Blue Shield plans,