Chapter 26 focuses on dynamic systems modelling, a rigorous approach for studying how causal interactions within a social-ecological systems (SES) lead to dynamics at the system level. Dynamical systems modelling provides conceptual, mathematical and computational tools to deal with key SES concepts such as feedbacks, non-linearity and regime shifts. The chapter discusses causal loop diagrams, loop analysis, qualitative analysis of differential equations (including bifurcation analysis and stability analysis) and numerical simulation of dynamical systems. It goes on to discuss the types of SES problems and research questions commonly addressed by this set of methods, as well as their limitations, resource implications and new emerging research directions. The chapter also includes an in-depth case study showcasing the application of dynamical systems modelling, and suggested further readings.