In recent years, dating and romantic partners have been recognized as important peer relations within adolescence and research in this area is just emerging. Peer groups and peer pressure are more well established areas of research into adolescence, with recent studies focusing on peer groups and anti-social behaviour. The book will be the first in a series of three that examines the latest research in key areas of developmental psychology, edited by Rutger Engels and Hakan Stattin. This volume will present four areas of peer research: the 'deviancy training' mechanism of peer influence; behavioural genetic analytical techniques in understanding peer selection; romantic partners as peer relationships; and in-school and out-of-school peers studies.