This paper reports on an investigation of adult online learning for 91 Taiwanese in-service preschool teachers enrolled in online degree programs. By using an open-ended written essay to investigate what learners thought they were learning through online education (their conceptions) and how they engaged in online education (their approaches), qualitatively different categories of conceptions and approaches were identified through a phenomenographic analysis approach. The results found that their conceptions of online education ranged from "a way of diploma completion" to "a way of lifelong learning," while their approaches ranged from "interacting with people" to "getting involved in the community of sharing." In addition, the teacher-learners with fragmented conceptions ("a way of diploma completion") tended to have surface approaches ("interacting with people"), and those with cohesive conceptions ("a way of lifelong learning") tended to have deep approaches in online education ("getting involved in the community of sharing").