This edited volume brings together an international perspective of 22 diverse learning theories applied to a range of informal science learning environments. The book is divided into 7 sections: community of practice, critical theory, identity theory, sociocultural, socioscientific, and social entrepreneurship, systems theory, and theory development. The chapters present how researchers from diverse backgrounds and cultures use theories in their work and how these may be applied as theoretical frameworks for future research. The chapters bridge theory and practice and collectively address a wide range of ages (children-adults) and contexts. The book is written to engage a broad audience of researchers in universities and museums, while appealing to the growing number of researchers and educators who recognize the importance of informal learning to the development of environmental and scientific literacy. It is essential reading for inexperienced researchers and those seeking new theoretical perspectives.