Agriculture can serve as a unifying and contextualizing topic that connects science, technology, engineering, and mathematics (STEM) subjects through similar knowledge, skills, and attitudes/beliefs (KSABs) exhibited in each. Agriculture can be an integral part of students' primary-level curriculum, providing authentic and relevant material for STEM exploration. A technology-enhanced, project-based, STEM-integrated agriculture curriculum for fourth-grade learners was developed and implemented in a large urban school district in the northeastern U.S. Ninety-five students and four fourth-grade teachers participated in a study that sought to (1) add to the existing knowledge about the nature of upper-primary urban students' agricultural literacy, (2) create a fully STEM-integrated agricultural literacy curriculum that educators can easily embed in existing curricula to increase literacy in agriculture and STEM fields, and (3) test the efficacy of that curriculum. The curriculum included valid and reliable pre- and posttest knowledge and attitudes instruments and eight performance tasks designed to help students prepare for a farmers' market. The findings revealed that students in the treatment group gained knowledge and had more positive attitudes/beliefs following the curriculum's implementation compared to a control group. Implications for creating integrated STEM and agriculture curricula using technology-enhanced, project-based learning strategies are discussed.