Two experiments were conducted to assess the performance of freshmen chemistry students with poor spatial visualization skills. In the first experiment, 31 chemistry students with academically deficient backgrounds completed a diagnostic test of their ability to visualize and interpret pictorial representations of simple molecular structures. At the end of their first semester of chemistry in a special academic support program, it was found that the 19 chemistry students who had failed the diagnostic test underachieved significantly as a group compared to the other 12 chemistry students, while no differences occurred between the two groups on an English language proficiency test. This finding was confirmed with 93 students enrolled in the traditional first year chemistry course, where students who failed the diagnostic molecular structure test underachieved consistently as a group, relative to their spatially able peers. (JDD)