The objective of the present study was to examine the effect of the activity-based oral expression course on the speech self-efficacy of psychological counseling and guidance students. The study group included 80 freshmen students in the Psychological Counseling and Guidance Department in the Faculty of Education of a university located in western Turkey. Quantitative data were collected with the "Speech Self-Efficacy Scale" developed by Katranci and Melanlioglu (2013). Qualitative data were obtained with the descriptive and content analysis of student views. It was found that the difference between the group averages obtained with the paired group t-test that was conducted on the measurement variable of the mean student speech self-efficacy scores was statistically significant (t (158) = -3.335; p = 0.001 <0.05). The posttest speech self-efficacy scores (x-bar = 96.025) were higher than the pretest speech self-efficacy scores (x-bar = 89.213). Based on the qualitative research the results of the present research demonstrated that students considered the activity-based oral expression course beneficial for all sources of self-efficacy beliefs, including direct experiences, indirect experiences, verbal persuasion and emotional state.