Involving students in inquiry-based exercises is much more difficult than simply providing activities for them to do in the classroom. While active learning suggests students are physically participating in the lesson, inquiry learning requires that they are also mentally participating in it. Academic theorists agree it is more the mental participation than the physical participation that is the important ingredient to enduring understanding. Students need to consciously consider the events they are exploring. They also need to actively examine what they possess and predict the ramifications of intervening with the action. While previous studies have shown that inquiry teaching can have a positive impact on learning, comparing college student performance taught by two different instructional methods in a science laboratory had not been done. The study reported in this paper compared introductory biology students taught lab through step-by-step directions with those taught through inquiry questions. The results of this study supported the contention that students from inquiry-taught labs learn more biology than students in classes with step-by-step directions, and they enjoy the investigations more than their traditionally-taught classmates. When compared, participants in the Experimental Group scored consistently better on the lab tests than students in the Control Group. The research also revealed that a significantly higher number of participants in the Experimental Group responded favorably about their experience in biology lab than did participants in the Control Group. In addition, the study found that students taught with the inquiry approach acquired enhanced science attitudes and reasoning skills during the year. (Contains 1 figure and 3 tables.)