Only a few instruments can monitor the quality of individual supervision sessions. Therefore, the first objective was to develop a brief Quality of Supervision Questionnaire (QSQ). The second objective was to examine person and context variables associated with more effective supervision sessions. Two online samples of n=374 psychotherapy trainees and n=136 supervisors were used to develop the QSQ using exploratory factor analysis, validity and reliability analyses, and tests for measurement invariance. In addition, correlations between the QSQ and person and context variables were examined. The final QSQ included 12 items and three factors (Effectiveness, Procedural Knowledge, Relationship). The supervisee version had good reliability (α=.83 to .88) and correlated moderately to strongly with convergent measures (r=.37 to .68). The supervisor version was partially invariant to the supervisee version, displayed weak to good convergent validity (r=.27 to .51) and mixed reliabilities (α=.67 to .81). Regarding person variables, higher session quality was positively associated with supervisee self-efficacy (r=.16) and being a supervisor (vs supervisee, d=0.33 to 0.56). Regarding context variables, there were significant effects for supervisors in cognitive behaviour therapy (vs psychodynamic therapy; in terms of Procedural Knowledge, d=0.86) and for competence feedback (vs no feedback; d=0.47 to 0.68), but not for individual (vs group-based) sessions. Overall, the QSQ is a valid and reliable self-report questionnaire. We discuss the conceptual overlap between supervision scales.

As a result of reading this paper, readers will:

1. (1) Be aware of the Quality of Supervision Questionnaire (QSQ), which is a brief self-report scale assessing the quality of individual supervision sessions with 12 items and three subscales: Effectiveness, Procedural Knowledge, and Relationship.

2. (2) Learn that there are no significant differences in the quality of supervision between sessions in individual and group formats. Compared with psychodynamic supervisors, supervisors in cognitive behaviour therapy report more procedural knowledge (i.e. what exactly to do and how to do it) in their sessions.

3. (3) Understand that supervisees evaluate sessions that included competence feedback as qualitatively better than supervisees who did not receive competence feedback.