Several factors have predicted participation in smoking cessation programs: (1) higher motivation or self-efficacy; (2) education; (3) smoking level; (4) smoking history; (5) quit attempts; and (6) health concerns. The variables that have predicted participation, however, generally have not predicted cessation. The transtheoretical model has described the stages and processes of change common to a variety of behavior changes. The stages have predicted changes in smoking behavior and an optimal pattern of stage by process activity has predicted quitting. This study explored the ability of the stages and processes of change, self-efficacy, and decisional balance to predict participation in group smoking cessation programs at three participation levels: (1) expressing interest in a cessation program; (2) selecting a specific program; and (3) attending a program's first session. The transtheoretical model's predictions for participation and quitting after 6 months were compared with those from a model based on demographic and smoking history predictors often cited in research. Subjects were volunteers selected from among self-change failures who had been participants in a longitudinal study evaluating minimal interventions for smoking cessations. The results indicate that transtheoretical model constructs are relevant for participation as well as cessation. In addition, smokers with higher levels of experiential processes like consciousness-raising are more likely to participate in the offered programs, and smokers who are more negative about smoking are more likely to ask for more help. Both the participation and quitting results provide further support for the transtheoretical model where higher levels of self-efficacy and behavioral processes contribute the most to change. (BF)