CPM(Conditional Probability Method) was devised as a simple method to handle the nonidealities of polymerizing systems. The key points of the method are to define clearly the probability of each event occurring in the system and to use conditional probability in formulating equations. Starting with this concept, we developed a systematic method which extended the existing theory. Furthermore, equations were derived separately for the sol and the gel by dividing all reactions into those between sol and sol, gel and sol, and gel and gel. Formulas for the ring forming parameter, number of rings, weight average molecular weight and number average molecular weight were obtained using this approach.