Some researchers have argued that the design of problems used in a Problem-based Learning (PBL) course or curriculum could have an impact on student learning cognitively or psychologically, such as students' self-directed learning process or engagement. To investigate the relationship between PBL problem design and students' self-directed learning as well as mindful engagement in the problem solving and learning process, this study explored two cases of PBL implementation in a Midwest university in the United States. Two classes of upper class college students participated in this study, including one wildlife management class and one classroom management class. The two classes underwent PBL instruction and solved a number of PBL problems. After the instruction, the students were surveyed about their perceptions toward the PBL problems. The data analysis and interpretation focused possible relationship between various elements of the problems and the students' self-directed learning process as well as their engagement during the PBL process. The similarities and differences between the two majors in terms of the students' perceptions were also discussed.