Introduction: Emotions have not been regarded as very relevant in educational processes, despite early sociologists underlining the importance of feelings in education. The focus of this research is on the teaching of Physical Education at the Primary School level in Spain. Method: We reflect on the importance of emotions in education from the sociological perspective and present a case study which examines the development of Physical Education through play in centres of primary education. In doing this, we have combined the use of participant observation and sociograms within an ethnographic framework. Results: Through our research, we demonstrate how, by working on emotions in the teaching of Physical Education, we can make a positive contribution to socialisation. Conclusion: This is possible because it is easier to develop positive emotions--and more effectively channel and constrain negative emotions - when we handle situations of cooperation and competition within a privileged socializing framework such as play. (Contains 6 footnotes.)