Of the 1100 planetariums in the U.S., approximately 96% are smaller facilities. The majority of these use a program type called the “Star Show”, whereas some have advocated a different type called the “Participatory Oriented Planetarium.” The purpose of this study was to investigate the following question: “In a smaller educational planetarium, with a capacity of between 15–75 people, is a traditional ‘Star Show’ planetarium program, or a ‘Participatory Oriented Planetarium’ program the most effective method of instruction and attitude change?” A large scale investigation was conducted in Pennsylvania, with four smaller replications in Texas, Minnesota, California, and Nevada. In each planetarium, a group of 8–10 year old students were identified and randomly assigned to groups. 556 students were tested. The testing instruments included a paper-and-pencil content test and a Likert-style science opinionnaire. The instructional programs were chosen from existing scripts to avoid bias in their construction. Both programs dealt with constellation study. Correlated t tests were used to compare pretest to posttest scores and two-way factorial analyses of variance were used to compare the groups' posttest scores. It was concluded that, “The Participatory Oriented Planetarium program, utilizing an activity-based format and extensive verbal interaction, is clearly the more effective utilization of a small planetarium facility for teaching constellation study and possibly for improving students' attitudes towards astronomy and the planetarium”.