Speeded tests set time limits so that few examinees can reach all items, and power tests allow most test-takers sufficient time to attempt all items. Educational achievement tests are sometimes described as "timed power tests" because the amount of time provided is intended to allow nearly all students to complete the test, yet this makes such tests speeded to some extent. Thus, speededness is often a matter of degree. Speededness can be impacted by factors in the test administration process such as test delivery mode, technology, and devices (Camara & Harris, 2020). Few studies have directly investigated the relationship between the extent that a test is speeded and the observed mode differences of the test. The purpose of this study was to investigate the potential interactions between the degree of speededness and observed mode differences in student performance for the ACT® test, a timed achievement test often used for academic planning and placement, college admissions, and scholarship eligibility. Based on prior research, it was hypothesized that more speeded tests would exhibit larger test delivery mode differences in test performance (i.e., paper testing versus online testing).