Motivation. All students studying Computer Science (CS) deserve to feel a sense of belonging. In a post-secondary CS class, undergraduate Teaching Assistants (TAs) have the majority of student contact hours, making student-TA interactions, such as those during office hours, important in shaping student belonging. Therefore, we sought to understand TA conceptions of belonging, their narratives about their journeys of belonging in CS, and how TAs influence student sense of belonging through office hour interactions.

Methods. We studied students and TAs at a large North American university in 4 CS courses, including introductory, intermediate, and advanced; core and elective, interviewing them about their belonging in post-secondary CS. We conducted semi-structured 1:1 interviews with 14 participants, consisting of 7 pairs of students and TAs who interacted in office hours.

Results. Student and TA conceptions and narratives of belonging aligned with the three basic needs for wellness as described in Self-Determination Theory: relatedness, competence, and autonomy. Some also surfaced needs for safety and access as key components of belonging. TAs and students reported that TAs supported student needs for competence, relatedness, and autonomy by fostering understanding of material, treating them with empathy, helping them see peers positively, and helping them to own their own success.