This Festschrift is dedicated to Gul Agha in recognition of his outstanding research and teaching impact. Gul Agha received his undergraduate degree at Caltech in 1977 and his A.M., M.S. and Ph.D. degrees at the University of Michigan, Ann Arbor. His thesis led to the MIT Press book Actors: A Model of Concurrent Computation in Distributed Systems, a work cited nearly 5000 times. After researcher and lecturer appointments at MIT and Yale, he moved to the University of Illinois, Urbana-Champaign, where he started as an assistant professor in 1989 and subsequently become a full professor and the founding director of the Open Systems Laboratory. The team's goal is to develop concurrent programming languages and systems that support applications with high-performance, fault-tolerance or real-time requirements, and this work has been very influential across domains such as Software Engineering, Formal Methods, Programming Languages, Concurrency Theory, Distributed Systems, and Cyber-Physical Systems. Gul Agha is a Fellow of the IEEE and a Fellow of the ACM, other honors include the IBM Faculty Award, the ONR Young Investigator Award, and the ACM Recognition of Service Award.

Over the course of his career Gul has been a highly impactful mentor, and he has collaborated in research and in publications with a wide range of scientists and engineers, in academia and in industry. Beyond his deep expertise, they have been inspired by his well-rounded intellect, philosophy of life, and sense of humor, and their successes are reflected in the papers contributed to this volume.