This article describes a new instructional model called Argument-Driven Inquiry (ADI). This model is designed to promote student engagement in processes of investigation design and scientific argumentation. In this study, the ADI instructional model is compared with a more traditional approach to instruction across 16 laboratory sections of introductory college chemistry. Data was collected pre- and post-intervention to address students' conceptual understanding of chemistry, ability to use evidence and reasoning to support a conclusion, and attitude toward chemistry. Results indicated significant differences between instructional approaches on measures of students' abilities to use evidence and reasoning while no significant differences in conceptual understanding were observed. Students in the ADI sections, particularly females, had a significantly more positive attitude toward chemistry, according to postcourse measures. Implications for the use of the ADI instructional model are discussed. (Contains 2 figures and 3 tables.)