Background: In previous research, the most common issues related to physical education in the primary classroom education are too extensive curriculum, negative attitudes of primary school teachers towards teaching physical education (PE), poor material working conditions, insufficient support from school management and low-level competencies of primary school teachers for the implementation of PE teaching. Therefore, the aim of this study was to investigate the relationship between (1) perceived supportive factors, (2) perceived competence and (3) attitudes of classroom teachers towards teaching PE and the quality of PE in primary education. Methods: The research was conducted on a convenience sample of 1598 employed classroom teachers in the central region of the Republic of Croatia during the 2009/2010 academic year. For the purposes of the research, a newly constructed comprehensive questionnaire, comprising five sections, was utilized for the research. Descriptive statistical indicators were calculated for all variables, and the relations between work determinants and the perceived quality of the PE lessons implementation was ascertained through a series of regression analyses. Results: The highest correlation with the variables describing the quality of PE teaching was found with the perceived competence of classroom teachers, accounting for 33% of the total quality of PE teaching variance. Perceived supporting factors and teachers' attitudes towards PE teaching also showed significantly and positive correlation with the overall quality of PE teaching. The strongest relation was found with job satisfaction and teacher attitudes towards the usefulness of PE teaching, which were significantly and positively related to all variables describing the quality of PE implementation. Conclusion: The findings suggest that in order to enhance the quality of PE teaching in primary education, emphasis should be placed on improving competency level, job satisfaction, and attitudes towards the usefulness of PE teaching among current and future classroom teachers.