Inquiry-based laboratories were implemented into a General Chemistry Laboratory sequence, and the impact of these exercises on students' experimental design skills was assessed using a four-part assessment developed for this study. This assessment contained a multiple-choice section, a section asking students to explain their reasoning behind a subset of the multiple-choice answers, an adapted form of the Experimental Design Ability Test, and a section asking about students' perceptions of themselves. For two years, pretests were administered before the students' first lab exercise, and post-tests were administered at the end of the year of General Chemistry Lab for cohorts of students enrolled in a Revised course and cohorts of students in an unchanged (Traditional) course. Overall, students in both the Traditional and Revised curricula experienced gains in learning outcomes as measured by comparing pre- and post-test scores on the first three sections of the assessment. Importantly, these gains were slightly higher for the Revised cohort on the multiple-choice section in Year 2 of the study. The quality of explanations on the second section of the assessment was also higher for the Revised cohort compared to students in the Traditional course. No significant differences were observed in average Experimental Design Ability Test performance. Student perceptions of confidence in their experimental design ability and their ability to conduct experiments were slightly higher for students who had completed the Revised course when compared to the Traditional course. In total, these modest improvements to students' experimental design abilities reflect a positive trend that supports implementation of inquiry-based laboratory instruction.