This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book focuses on research by those with hands-on playwork experience and offers some insights and provocations from the researchers from other disciplines. Playfulness has been explained as “an attitude of the mind”. Playworkers spend time with children in a way that is playful and engaging and does not always reflect perceived ‘good practice’ in other professions. The book argues that designing playfulness into the data collection stage relaxes children and redresses the power balance between children and adults, and therefore creates more meaningful data. It discusses the potential dangers of adulterating and annihilating children’s play flow in the name of research, and also notes that working to children’s agendas around issues such as participation can limit the research design and ultimately the research findings.