DROSHA and its partner DGCR8 form a heterotrimeric complex named Microprocessor, which is essential for microRNA biogenesis. A recent study by Kwon et al. in Cell reveals the structure of a DROSHA construct in complex with the C-terminal region of DGCR8, thereby unveiling the topology and interactions between components of the Microprocessor and insights into its 'ruler'-based cleavage activity and function.