A study was conducted to investigate the extent to which previous science achievement affected student performance in traditional hands-on and virtual laboratory environments. A sample of 70 first-year college students was employed in a counterbalanced A-B-A-B experimental design. The study spanned four instructional weeks of laboratory experimentation alternating traditional and virtual learning environments. For each of the four labs, students were given a pre-test designed to measure content knowledge, administered the intervention of virtual labs, and this was followed by an identical post-test. Prior science achievement was assessed using a general chemistry assessment exam. T-tests revealed that student performance did not differ between the hands-on and virtual environments. Results of a MANOVA showed that virtual labs were more effective than hands-on labs for high-achieving students, whereas there was no difference for low-achieving students. Results of a second MANOVA revealed that high-achieving students outperformed low-achieving students on hands-on lab 3, virtual lab 3, and hands-on lab 4. Findings suggest that the use of virtual labs does not harm science achievement and may conserve resources, but may expand the gap between high- and low-achieving students in the science laboratory. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]