In many countries around the world, there has been an increasing emphasis on improving science education. Recent reform efforts in the USA call for teachers to integrate scientific and engineering practices into science teaching; for example, science teachers are asked to provide learning experiences for students that apply crosscutting concepts (e.g., patterns, scale) and increase understanding of disciplinary core ideas (e.g., physical science, earth science). Engineering practices and engineering design are essential elements of this new vision of science teaching and learning. This paper presents a research study that evaluates the effects of an engineering design-based science curriculum on student learning and attitudes. Three middle school life science teachers and 275 seventh grade students participated in the study. Content assessments and attitude surveys were administered before and after the implementation of the curriculum unit. Statewide mathematics test proficiency scores were included in the data analysis as well. Results provide evidence of the positive effects of implementing the engineering design-based science unit on student attitudes and learning.