This article examines the intersection of service-learning with complex systems theory. It is based on a research project we undertook to explore whether complex systems theory might be useful for better understanding the dynamics of service-learning practice and thus for assisting in the design, running, and evaluation of service-learning projects. Additionally, we were interested to find out whether the specifics of our service-learning experience and knowledge, what we refer to as "critical service-learning," might have something of value to contribute to the interdisciplinary and ever-broadening paradigm of complexity studies. Our findings respond to these two tasks in the affirmative: We conclude complex systems theory can be of benefit to service-learning practice in a conceptual, operational, and strategic capacity. In instances where critical service-learning practice initially appears to be incongruent with complex systems theory, conversely these instances instead highlight precisely how service-learning could advance the analysis of systems in complexity studies.