The key to Market Systems Development lies in using systems principles and frameworks to understand the underlying causes of challenges (“why?”) in order to identify system-level changes to respond to them (“what?”), and to guide interventions that can bring lasting change (“How?”) This three-part series on MSD fundamentals developed by the Canopy Lab –  with support from independent consultants Mike Klassen, Samira Saif, and Kelsey Bachenberg – presents key components and tactics (#1), MSD litmus test questions (#2) and common myths surrounding the approach (#3).