The purpose of this research was to investigate the incorporation of Structured Problem Solving in a Lesson Study initiative in Ireland. Since 2014, an annual average of 150 post primary mathematics teachers across 83 schools have participated in Lesson Study as a form of professional development. This has resulted in a published bank of research lesson plans, 145 of which were included in this research and analysed based on a framework of Structured Problem Solving. The results revealed strengths (e.g. students presenting their solutions) and weaknesses (e.g. teachers summarising lesson content) in the research lesson plans. The findings provide key insights for professional development regarding the incorporation of Structured Problem Solving in mathematics lessons and include recommendations for further research in this field.