ABSTRACT Toddler milk (i.e., an ultra-processed milk-based drink marketed to toddlers) is increasing in popularity in the US and globally. However, toddler milk is not recommended by medical and pediatric associations, because it usually contains added sugar, and early consumption of added sugar is associated with obesity and type 2 diabetes. Toddler milk packaging contains front-of-package (FOP) claims marketing the supposed “benefits” of the product. Such marketing claims are not regulated by the Food and Drug Administration (FDA) and may mislead parents about the healthfulness of toddler milk. There is a significant gap in understanding how marketing elements on toddler milk packaging influence parents' perceptions of and beliefs about the product. This gap represents a critical public health problem because understanding how marketing claims on toddler milk packages affect parents is necessary to inform labeling policy and prevent parents from exposure to information that is not supported by science. This project examines how toddler milk marketing influences parental perceptions and beliefs via a systematic review, packaging content analysis, and focus groups with parents. Using primary and secondary data, this study aims to: 1) Describe the determinants of toddler milk purchasing and the influence of marketing on parents’ beliefs and behavior by conducting a systematic review. Under this aim, the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement will be used, and the existing literature around toddler milk labeling will be synthesized; 2) Describe the nutritional qualities and FOP marketing claims of the top 5 toddler milk brands in the United States and 22 Latin American countries by conducting a content analysis of toddler milk FOP labels. This aim will elucidate and quantify food companies' labeling marketing practices around toddler milk; and 3) Explore how marketing exposure, including reactions to FOP claims and warnings, influences parents' perceptions, beliefs, and use of toddler milk. Focus groups with parents of toddlers will provide in-depth knowledge about how and why the marketing practices identified in Aim 2 affect parents' perceptions and beliefs. The overall training objectives are to develop a theoretical understanding of how marketing practices influence consumers' perceptions and beliefs while developing skills to conduct systematic reviews, content analysis, and focus group data analysis. The proposed research fits with NICHD's mission of “enhancing the lives of children,” and is timely and significant because it will generate both an understanding of how food labeling influences parents and evidence to support food labeling policy change. Ultimately, such knowledge has the potential to inform the FDA so that it can regulate toddler milk packaging and protect parents from feeding their children an unhealthy product during a crucial phase of development.