This was an experiment to test the extended discretion laboratory approach (ED) versus a guided-inquiry (GI) approach for teaching biology in a university setting. It had previously been found productive in a high-school setting. The approach provides considerably less specific procedure for the students to follow than did a guided-inquiry approach and required relatively high independence. Four hundred sixty-nine students taking university introductory biology were randomly assigned to using either the ED learning approach or one characterized as guided inquiry for one semester. Three measures were taken to verify that instructional treatments followed the two approaches. All indicated qualitative and quantitative differences between ED and GI approaches in the direction predicted by the operational definitions. The criterion variables were (1) student scores on a multiple-choice laboratory exam, (2) student scores on laboratory reports, and (3) student scores on six laboratory quizzes given during the semester. The only criterion variable which showed significant differences between groups (laboratory-report scores) also showed significant group-by-instructor interaction. The hypothesis of no difference therefore stood unrejected for all criterion variables. Since the ED approach appears to produce equivalent learning gains in understanding of biology laboratory concepts compared to a guided-inquiry approach, this approach should still be considered for laboratory teaching, because it purports to train for discretionary use of resources during instruction in addition to the conventional development of laboratory concepts.