Can love and conflicts in partnerships, or the security a mother provides to her child, be studied scientifically, even measured? How do relationships change? How do they vary from culture to culture? This book offers a systematic overview of all important types of relationships. It covers romantic relationships, parent-child and sibling relationships, friendships, work relationships, and neighborly relationships. Seven paradigms of relationship research are discussed - from Freud's ideas to cognitive and evolutionary psychological approaches, attachment and exchange theories, and systemic and network approaches - all integrated into a cohesive relationship model. The second edition has been completely revised and updated to reflect the latest research. New topics include kinship, motivational approaches, and relationships in social change and multi-ethnic contexts. Additionally, current issues such as online dating and relationships in social online networks are addressed. A new feature is a separate methods chapter that presents specific research methods and application procedures in an easily understandable manner.