The purpose of this study was to examine the effects of testing on the achievement of students using self-instructional materials to learn science process skills. In one section of an undergraduate science method class, students were paced through a programmed textbook and were given short quizzes in class after each of the process skill lessons was assigned, while in another section, students worked at their own pace and were held responsible for completing the lessons by the end of the semester. Students taking the quizzes throughout the semester were expected to attain a higher level of process skill proficiency because previous studies have shown that taking a test immediately after learning leads to better retention of the material. Results indicated that taking frequent quizzes did not differentially affect process skill acquisition.