Continued professional development (CPD), tailored to teachers' needs and expectations, is required for updated skills and knowledge. In this study, twenty-five teachers working with first and second grade students participated in an 11-week programme focusing on enhancing classroom communication. The participating teachers were randomly assigned to either a direct intervention track (intervention) or a delayed intervention track (waiting control). Teachers' perceptions of activities and interactions in the classroom and self-efficacy were assessed on three occasions: T1, T2, and T3. The direct intervention track received intervention between T1 and T2, while the delayed intervention track received intervention between T2 and T3. A percentage change score for changes between T1 and T2 was calculated, to compare the direct and delayed intervention tracks and assess any intervention effect. Results revealed no significant difference between the groups, i.e., the intervention had no effect on teacher self-reports. The teachers gave an overall positive evaluation of the CPD. Thematic analyses revealed continued need for professional development and insights into the reciprocal influence of student and teacher behaviour. The quantitative and qualitative results paint somewhat different pictures showing the need of mixed methods when analysing these kinds of data.