This research examined the effects of structured group supervision (SGS) on counsellors' self-efficacy, counselling competency, and job involvement in Singapore. Twenty-one counsellors participated in six, 3- hour SGS sessions over 12 weeks with one qualified counselling supervisor. The counsellors had at least six months' experience working as counsellors in schools or educational-related settings, such as student care centres. A single-group, before-after design was adopted. Pre- and posttest questionnaires were administered--Counselling Self-Efficacy Scale (CSES), Counsellor's Competence Self-Evaluation Scale (CCSS), and Job Involvement Scale (JIS)--to examine counsellor self-efficacy, counselling competency, and job involvement respectively. Paired-sample t tests were used to examine the impact of SGS on the three measures, whereas the Pearson correlation was used to examine the relationships among them. It was found that there was (a) a significant increase in mean scores for pre- and posttest scores for counsellor self-efficacy and counselling competency, but not for job involvement after SGS; and (b) a significant positive correlation among the three variables. With a better understanding of the SGS and the impact on counsellors, supervision practices can be improved and school counsellors can become more competent and confident.