This study's main purpose was to identify adult learners' motivation to pursue learning at Saudi Arabia's Yanbu adult-education schools. The study also investigates if there is a difference by gender, by age, and among learners in terms of their internal and external motivation to learn. The study's theoretical framework came from Knowles' theory of andragogy. A survey consisting of a self-administered questionnaire was used. The study population included all adult learners (n = 463) at the Yanbu adult-education schools in Saudi Arabia. The results revealed the importance of the five motivators (social contact, family togetherness, social stimulation, cognitive interest, and religious stimulation) for adult learners at Saudi Arabia's Yanbu adult-education schools. However, this study indicated that adult learners are more motivated internally than externally. Therefore, teachers should pay attention to the internal factors more than the external factor to keep up with their students' level of motivation.