Financial stress is the root cause of many adverse health outcomes among poor and low-income children and their families, yet few clinical interventions have been developed to improve health by directly addressing patient and family finances. Medical-Financial Partnerships (MFPs) are novel cross-sector collaborations in which health care systems and financial service organizations work collaboratively to improve health by reducing patient financial stress, primarily in low-income communities. Financial services provided by MFPs include individually tailored financial coaching, free tax preparation, budgeting, debt reduction, savings support, and job assistance, among others. MFPs have been shown to improve finances and, in the few existing studies available, health outcomes. We describe the rationale for MFPs and examine eight established MFPs providing financial services under 1 of 3 models: full-scope on-site service partnerships; targeted on-site service partnerships; and partnerships facilitating referral to off-site financial services. The services MFPs provide complement clinical social risk screening and navigation programs by preventing or repairing common financial problems that would otherwise lead to poverty-related social needs, such as food and housing insecurity. We identify common themes, as well as unique strengths and solutions to a variety of implementation challenges MFPs commonly encounter. Given that the financial circumstances and health outcomes of socially marginalized patients and families are closely linked, MFPs represent a promising and feasible cross-sector service delivery approach and a new model for upstream health care to promote synergistic financial well-being and health improvement.