Only one third of adult trainees transfer what they learn merely 1 year after training, and the amount of knowledge applied is less than 40% of what they learned. Transfer of learning becomes more critical for those in train-the-trainer programs where future success or failure is shaped by previous outcomes. Consequences compound even further in safety-related contexts, such as skydiving, where certain aspects of training correlate with injury rate. The problem addressed in this study was the low transfer of learning that exists in adult training. The purpose of this quantitative quasi-experimental study was to examine the effect of course modality on learning transfer, specifically among skydiving teachers-in-training in coach rating courses in the United States using a Solomon four-group design, guided by the theories of andragogy and connectivism. Intact classrooms comprised of 28 participants were randomly assigned to one of four groups: two groups were pretested and two were not; all were post-tested; treatment was given to one pretest-posttest group and posttest-only group. Learning transfer was measured using the Learning Transfer Systems Inventory, deemed valid and reliable to predict learning transfer. The Braver and Braver (1988) meta-analytic guided the data analysis. Results revealed no significant difference between the pretest and posttest learning transfer scores. However, a statistically significant difference in posttest learning transfer scores existed between those in the flipped classroom compared to those in the traditional classroom, unqualified by pretest sensitization and controlling for pretest learning transfer scores, with a moderately large effect size, F(1, 5) = 11.55, p = 0.02, partial [eta-squared] = 0.70. These findings underscore the importance for educators, curriculum developers, and instructional designers to consider flipped classroom modality for improving transfer of learning in adult training and teachers-in-training programs. The study recommends future educational researchers use the Solomon four-group design for its capability of producing rich and nuanced findings. Researchers and educators are encouraged to look beyond course test scores toward learning transfer as a more impactful metric. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]