Between 2014 and 2017, an interdisciplinary group of researchers examined whether a high school health class that incorporated mindfulness techniques lowered students' stress and improved their wellbeing. We received a grant from the Institute of Educational Sciences from the United States Department of Education to (1) train high school health teachers to implement the mindfulness-based curriculum and (2) study how the program impacted students. We examined changes in cognitive, social, emotional, and physical wellbeing indicators from before the course to after the course, using a quasi-experimental (intervention and control group with pre and post tests), mixed-methods (concurrent triangulation) design. Data consisted of student responses to psychometric surveys and interviews with a subsample of students. When we compared qualitative findings with quantitative outcomes, we discovered instances of different results through each method. This allowed us to provide explanations and context for certain outcomes. For example, the recent loss of a grandparent explained why one student scored high in social isolation. At other times, the two methods found two different "outcomes stories" from the same student. For example, a student reported in the interview that he was struggling with social interactions, but the psychometric indicators had him in the top quintile of social wellbeing indicators as compared to his peers. This case study discusses methodological approaches to mixed-method educational psychology research, the challenges of making sense of data from different sources, and the usefulness and limitations of mixed-methodologies for psychological outcome evaluations of student wellbeing interventions. We also discuss the process of working as a large group of researchers. This case is useful for students in psychology and education, and it is equally useful for early career researchers.