As part of a larger project to integrate advertising literacy into school curriculum, this research evaluates the effectiveness of an initial three-hour advertising literacy classroom intervention among eight- and nine-year-olds. The field experiment (a pretest/posttest, control/experimental group design) was implemented in 10 third grade classes in a three-week time period in three high-poverty schools in the United States. Low advertising literacy occurred at baseline. Evaluation results indicated significant increases in intervention students' understanding of the message creator, the selling intent, persuasive strategy, and target audience. Recommendations for curriculum development, refinement, and implementation for a wider audience are discussed.