We introduce this two-part special issue that celebrates David Heise and his pathbreaking theories: affect control theory (ACT), affect control theory of the self (ACTS), and affect control theory of institutions (ACTI). These interlocking, multi-level, mathematically based theories explain a range of social processes, including impression formation, social interaction, trait and mood attributions, emotional experiences, emotion management, and identity adoption, and they do so in multiple languages and cultures. The 15 articles in this two-part issue test, apply, and develop the theories in new and innovative ways. After briefly summarizing each theory and Bayesian affect control theory (BayesACT), we highlight the key findings from each of the articles that follow.