This study explores Finnish chemical engineering students' peer and self-assessment perceptions. It is divided into two substudies. In Study I, we investigate students' perceptions of peer and self-assessment based on their responses to open questions and Likert-items adopted from existing literature. We identify six perception dimensions from these open responses: Learning and reflection, Motivation and participation, Self-efficacy, Exhaustion and workload, Cynicism, and Self-criticism. In Study II, we develop a new questionnaire for engineering students' peer and self-assessment perceptions, as pre-existing questionnaires fail to adequately capture these dimensions. Exploratory factor analysis is used to investigate how student perceptions form larger factors, and how they relate to theoretically connected pedagogical measures like study-related burnout, self-efficacy, and learning approaches. We find that negative perceptions correlate with study-related burnout and an unreflective approach to learning. Meanwhile, positive perceptions of self-efficacy and learning in peer and self-assessment are associated with the deep approach, underlining the importance of facilitating positive assessment experiences in students.