The concept of "student engagement" is widely discussed in academic libraries, but has not been thoroughly examined from a conceptual and theoretical perspective by scholars in the Library and Information Science (LIS) field. This paper presents the findings of a qualitative research project on student engagement in academic libraries. Through in-depth interviews conducted at four academic libraries, and utilizing a flexible coding data analysis strategy, we propose a conceptual framework with antecedents, dimensions, and outcomes. This framework sheds light on the nature of student engagement in academic libraries. The process model can guide student engagement planning, communication, and evaluation efforts in academic libraries.