This edition of Family Matters highlights a diverse body of research on children in their family contexts. It is stimulated by the recognition that a 'one size fits all' conception of family is no longer tenable, and that understanding and supporting children's development in the current wide array of family forms is needed. This introductory article reviews attempts to disentangle the effects on children of family form or family structure from the effects of intra family and extra family processes. It sets the scene for the subsequent papers in this edition, where the common underlying concern is how children and their families and parents can best be supported, whatever their family form and context to provide for children's healthy development.