Book excerpt: From their location in the heart of Detroit, Michigan, the Weisfelds’ lab has reached out for thirty years to couples in long-term partnerships around the world. In living rooms of Detroit, London, Moscow, Beijing, and beyond, couples of all types and ages have shared their insights into adult romantic relationships. This book, The Psychology of Marriage, is a distillation of these findings, which have appeared in dozens of book chapters, journal articles, and conference presentations. The book also provides new systematic comparisons that offer insights into the mysteries of marriage and other committed relationships. Scholars, professional counselors, and family therapists will find a helpful framework for thinking about cultural similarities and differences in marital dynamics. Researchers will be introduced to a robust new instrument, the Marriage and Relationship Questionnaire (MARQ), which can be used in heterosexual and same-sex couples in virtually any cultural setting, along with ethical guidelines for conducting this research. Anyone who is interested in why committed relationships work (or do not work) will find the book filled with compelling new insights.