Romantic love is ubiquitous and has major influences on people's lives. Because romantic love consists of infatuation and attachment, researchers need to be able to differentiate between these constructs when examining the behavioral, affective, cognitive, and physiological correlates of this intriguing phenomenon. Existing love questionnaires appear less suitable for measuring the two-dimensional construct of romantic love. We present here the new 20-item Infatuation and Attachment Scales (IAS) questionnaire. In Study 1, exploratory factor analyses in a Dutch-speaking sample (n = 162) revealed a clear-cut two-factor structure, with 10 infatuation and 10 attachment items loading on separate components. This two-factor structure was confirmed in a new Dutch-speaking sample (n = 214, Study 2), and in an English-speaking sample (n = 183, Study 3). In all studies, it was additionally shown that both scales possessed good convergent and discriminant validity, as well as excellent internal consistency and test-retest reliability. We argue that the IAS is a widely applicable, psychometrically sound instrument that will be useful in future research exploring the effects of infatuation and attachment on behavior, emotion, cognition, peripheral physiology, and brain functioning.