Why are these groups often so great, so welcome, so precious? Real life is very rich - theories only capture aspects of this richness. However a theory, that I like a lot, highlights one reason why these peer groups are so important. The theory is Self-Determination Theory (SDT). It has evolved for over three decades. The SDT website (see below) is a treasure trove of information about this approach. It contains hundreds of research papers covering SDT's application to many fields including happiness, wellbeing, friendship, couples, parenting, education, psychotherapy, healthcare, political/ecological action - to name just some of the more obviously relevant.
SDT focuses particularly on the crucial importance of satisfying three basic psychological needs - autonomy, competence and relatedness. It proposes that: