This paper describes the design, implementation, and evaluation of an inquiry-based laboratory for sophomore-level organic chemistry into a mostly cookbook, existing laboratory curriculum. For the laboratory, students were required to generate their own procedures and use their own recorded data from prior laboratory assignments to identify an unknown compound; all unknown samples were student-synthesized products from previous laboratories. The laboratory was designed to increase student involvement in the experimental design process and promote student reflection on their prior laboratory experiences. This laboratory was implemented during a single laboratory period across eight sections of the second-semester organic chemistry laboratory. Surveys were administered before and after the laboratory and analyzed to investigate student perceptions of their self-reported confidence in their laboratory skills, their laboratory notebook usage as a record of data, and their overall impressions of the laboratory. Students reported an increased confidence in laboratory skills and an improved recording of data in their laboratory notebooks. The majority of students appreciated the self-directed nature of the laboratory and felt, overall, that it was a good review of laboratory skills that encouraged them to reflect on their learning. The laboratory was readily added to an existing laboratory curriculum with low cost of time and materials and high benefit to students. Recommendations for implementation in first- or second-semester organic chemistry, including how to adapt this approach to other institutions' existing laboratory curricula, are provided.