Student-athletes in university undergo assessments in both sport and academic domains, which can encompass varying conceptions and outcomes related to assessment. However, questions on whether this 'doubling up' of assessments result in similar or different assessment-related outcomes, or whether assessments are conceived the same way across sport and academic contexts, are an omission in achievement research. This study sought to explore the experiences of Canadian student-athletes' conceptions of assessment, perceptions of control, and emotions in sport and academia through an explanatory mixed-methods design. The study comprised 77 Canadian USports university athletes (M[subscript age] = 20.21) for the quantitative data, and 6 athletes partaking in focus group/individual interviews for the qualitative data. The quantitative findings revealed student-athletes reported higher conceptions of assessment as fun and irrelevant in sport compared to university, and greater emotions such as anger, helplessness, and relief in university compared to sport (p < 0.05). In the qualitative strand, three themes were identified for conceptions of assessment: function, discrete outcomes, broad consequences; three themes for perceptions of control: effort, preparation, and motivation; and three themes for emotions: anticipatory, retrospective, and relational. Mixed insights revealed the importance of assessment consequences, the natural motivation and effort for sport assessment, and the differences in positive and negative emotions between sport and academic domains. Recommendations are discussed for both postsecondary coaches and instructors to help improve sport and academic assessment in ways tailored to the student-athlete experience of assessment.