Book excerpt: Measuring and Modeling Persons and Situations presents major innovations and contributions on the topic, promoting deeper integration, cross-pollination of ideas across diverse academic disciplines, and the facilitation of the development of practical applications such as matching people to jobs, understanding decision making, and predicting how a group of individuals will interact with one another. The book is organized around two overarching and interrelated themes, with the first focusing on assessing the person and the situation, covering methodological advances and techniques for inferring and measuring characteristics, and showing how they can be instantiated for measurement and predictive purposes. The book's second theme presents theoretical models, conceptualizing how factors of the person and situation can help us understand the psychological dynamics which underlie behavior, the psychological experience of fit or congruence with one’s environment, and changes in personality traits over time. Identifies technologies for measuring and predicting behavior Infers behavior causes from personality and/or situational variables Utilizes big data, machine learning and modeling to understand behavior Includes mobile phone, social media and wearable tech usage analysis Explores the stability of personality over time Considers behavior analysis to treat maladaptive behavior