Background: Incorporating assessment as a regular practice can enhance teaching and learning in primary physical education. However, there is little evidence to suggest primary teachers use assessment strategies regularly in their physical education classes. Purpose: To explore the impact of incorporating assessment into primary teachers' physical education practices on (a) their perspectives on assessment and (b) teaching and learning in primary physical education. Methodology: Primary teachers in Limerick (n?=?2) and Dublin (n?=?3) participated in initial focus group interviews exploring practices and understandings of assessment in physical education. Each teacher then planned and delivered a series of lessons where assessment was considered in relation to the learning intentions. Their experiences were captured using reflective journals (Limerick) and a mid-point focus group interview (Dublin). Both groups of teachers participated in a third focus group interview after lessons were completed. Qualitative analysis by both researchers involved individual coding of the data using the constant comparison method followed by conversations on alignment of findings. Trustworthiness of the data was addressed using peer debriefing techniques. Findings: The inclusion of assessment in physical education lessons provided structure and focus to the planning, teaching and learning processes and impacted positively on both teacher learning and the children's learning. The assessment strategies focused the learners, allowed for feedback related to assessment criteria and informed future planning. Challenges for the teachers included the amount of time needed to plan, difficulty in accessing sample assessments and differentiating assessments for different class levels and abilities. Conclusion: The use of assessment strategies enhanced the quality of teaching and learning in physical education and impacted positively on the teachers' and learners' perceptions of physical education. The importance of supporting teachers, through provision of information on assessment strategies and samples of assessment strategies aligned with content in physical education to enhance their everyday practice, is highlighted.