Nutrition labeling interventions are designed to provide consumers with easily interpretable nutritional information at the point of purchase. Despite the widespread implementation of these interventions and numerous research studies, there is little consensus as to their effect on consumer behavior. To address this issue, a novel methodology of second-order meta-analysis was utilized to provide a comprehensive synthesis of prior research on nutrition labeling effects. The difference in effects across published first-order meta-analyses was investigated based on whether the aim of the intervention was to prevent the consumption of unhealthy food or promote the consumption of healthy food (prevention vs. promotion focus). The extent to which the aim of the intervention impacts other intervention and study characteristics in study outcomes was additionally examined. Analysis of 93 first-order meta-analysis effect sizes highlighted differences according to whether the aim of the intervention was to prevent the consumption of unhealthy food or promote the consumption of healthy food. Differences were identified in the size of nutrition label effects for various label types, label location, and study and sample characteristics. In addition to important public policy implications, this research contributes to the ongoing discussion on the merits and limitations of meta-analysis methodology.