Standardized tests like the ACT® provide a common basis for comparison of students across schools and states and have been a key point of consideration in postsecondary admissions for over 60 years. Research has shown that, in general, test preparation has a small but positive effect on standardized test scores. In this study, we focused on how three different test preparation formats--in-person instruction, self-paced, and other types--related to students' ACT Composite scores. We examine whether there is a relationship between type of preparation activity and ACT Composite score and whether that relationship depends on family income or whether students are first-time or repeat ACT testers. For the total sample, we found no significant effects of test preparation on ACT Composite. We also found that the effects of the different preparation formats did not vary by family income. Furthermore, the number of times tested had an impact on ACT scores, and this effect differed by test preparation format. First-time test-takers who participated in self-paced test preparation had a lower ACT Composite score than those first-time test-takers who did not participate in a test preparation activity. This study does not align with past research that shows a small effect of test preparation on ACT scores. Our study might not have detected an effect because of the research design or the sample of students who participated in the survey. Or, heterogeneity in the quality, methodology, and modes of delivery within each test preparation format may have blurred any effects.