Strategic flexibility is widely accepted as a capability that helps organizations deal with uncertainty. It can be particularly crucial for young ventures’ survival and growth. However, how individuals contribute to the emergence and evolution of strategic flexibility and how young ventures develop this capability remains under-researched. To address this gap, we investigate how founding CEOs contribute to the strategic flexibility of their venture. Based on a qualitative analysis of 28 young ventures, we develop a typology of decision rules founders use that function as microfoundations of strategic flexibility. With this typology we present a system-based approach for enabling strategic flexibility in young ventures. Furthermore, we also highlight the negotiated nature of strategic flexibility and the tensions that need to be managed to configure this capability.