The Supplemental Nutrition Assistance Program-Education (SNAP-Ed) is the nutrition promotion component of SNAP, formerly known as food stamps. SNAP-Ed assists low-income populations in the United States improve dietary intake and reduce food insecurity through nutrition education. This narrative review summarizes current investigations of SNAP-Ed's effectiveness at improving food security and dietary outcomes, and it can help inform future policy and implementation of the program. There was stronger evidence for SNAP-Ed as an effective means of improving food security (n = 4 reports) than for its effects on nutrition or dietary outcomes (n = 10 reports). Inconsistency in measurement tools and outcomes and a lack of strong study designs characterized the studies that sought to evaluate the effectiveness of SNAP-Ed at improving nutrition or dietary outcomes. Additional rigorous study designs in diverse population groups are needed to strengthen the evidence. In the face of reduced financial SNAP benefits, SNAP-Ed may play an important role in helping to eliminate food insecurity and improve dietary outcomes and, ultimately, the health of low-income Americans.