Background: As nutritional needs increase in adolescence, dairy consumption can play a key role in health and disease prevention; however, unfortunately, inadequate consumption of milk and dairy products has often been reported in adolescents. Aim: The purpose of this study was to investigate the relation between decisional balance, self-efficacy, and the processes of change with the stages of change for dairy consumption in female high school students in Shaft county located in the west of Gilan Province, Iran. Methods: A total of 385 female high school students in Shaft County were studied through the census method in 2019. The data collection instrument was a valid and reliable questionnaire consisting of demographic information, stages of change and items of transtheoretical model constructs including the processes of change (cognitive process: consciousness-raising, dramatic relief, self-reevaluation, environmental reevaluation, and social liberation; behavioral process: self-liberation, counter conditioning, reinforcement management, stimulus control and helping relationships), decisional balance and self-efficacy. Data were analyzed using SPSS 21 software. Results: A total of 208 (54%), 53 (13.8%), 56 (14.5%), 32 (8.3%) and 36 (9.4%) students were in the pre-contemplate, contemplation, preparation, action and maintenance stages, respectively. As the subjects progressed through the stage of change for dairy consumption, an increase in the mean score of self-efficacy, decisional balance, and processes of change was observed (P < 0.01). Conclusion: The constructs of the transtheoretical model should be considered in designing educational interventions to promote dairy consumption with regard to the stage of change for dairy consumption in the subjects.