Agent banking and mobile money networks are essential for extending financial services to underserved populations, particularly in rural areas of low- and middle-income countries. The sustainability of these networks depends on the financial viability of the agents. This brief, drawn from Evidence and Gap Map for the Retail Finance and Distribution Initiative, examines the relationship between network expansion and agent and merchant viability, exploring whether and how growing agent networks affect the profitability, retention, and long-term sustainability of agents.