Objective: To identify and review data collection techniques used to measure preschool children’s knowledge of food and nutrition. Design: A systematic review of published research guided by the Preferred Reported Items for Systematic Reviews and Meta-analyses statement. Participants: Published journal articles between 1980 and 2013 reporting research involving the measurement of preschool children’s (aged 3–5 years) knowledge of food and nutrition. Results: Twenty studies were eligible for inclusion. The studies reported the use of a range of innovative age-appropriate techniques to assess children’s knowledge of food and nutrition. Data collection techniques were grouped under 3 broad approaches: (1) interviews, (2) use of stimulus material and prompts, and (3) structured play-based activities. Only 3 of the reviewed studies tested for both reliability (test-retest and internal consistency) and face and content validity. Only 9 of the reviewed studies reported pilot-testing their instruments before use. Conclusions and Implications: Results from this review suggest that additional research is needed to develop more valid and reliable measures to assess preschool children’s knowledge of food and nutrition. Assessment tools need to be pilot-tested, refined, and adapted to suit both the specific audience and the components of the nutrition knowledge being targeted by an intervention before implementing a nutrition education program.