Adult learning practices that incorporate experiential learning and playfulness promise greater learner involvement and engagement, produce better results than "teaching-to-the-test" lectures and presentations, and represent a major opportunity to improve adult learning. The author developed such an adult learning activity for an adult Safe Boating class. This study used this playful adult learning activity (PALA) to experimentally compare learning experiences between PALA and Control classes with eighty-nine (89) subjects who volunteered from a population of boaters in the North East United States. Using surveys, quizzes, and interviews, this longitudinal mixed-method study spanned three contacts with subjects over an average of 131 days, including transfer of learning to real-world boating experience. Results show that the PALA is significantly more effective for learning and retention than presentation alone, but it was even more effective for less experienced boaters. This study examined the value of playfulness beyond the classroom, and the subjects testified to outcomes such as greater confidence, improved awareness and perception, and a more safety-conscious attitude, often tied to a more interactive and socially-aware relationship with family, friends, and others. The findings suggest other benefits from PALA for most groups in the population. This study addresses a lack of experimental studies of playfulness and experiential adult learning in the literature. It suggests a need for changes and extensions to theoretical models along with a need for more research into playful adult learning activities. It recommends that experiential learning with playfulness should be widely adopted for safety, compliance, and certification training. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]