Academic spin-offs have become widely recognized vehicles for the commercialization of research results, fostering regional growth by universities. However, expectations of benefits are accompanied by high failure rates, low survival rates and fragile development paths. Our study addresses the role and contribution of the parent university in ASO growth. While most prior research focused on external contingencies relevant for successful ASO development, we turn towards the relationship between the parent university and the ASO in order to better understand how its dynamics can support or impede growth. From a behavioral perspective, we argue that these relationships are consequential to the behavior of ASO entrepreneurs, their attention focus and their business development. Our study focuses on trust- and distrust-building mechanisms between the ASO and its parent university. In order to identify relevant patterns experienced by individuals, we use a purposeful sampling procedure for maximum heterogeneity. We collected 19 semi-structured interviews from 29 informants at the same research university, along with its 10 ASOs at various stages of development and from diverse academic fields. We follow a hybrid coding procedure, and thematically group emerging topics into overarching themes to find that trust and distrust appear at the same time within the same relationships. The interplay between trust and distrust appears as asymmetrical and ambivalent. We identify the mechanisms that lead to trust and to distrust at the individual and institutional levels. Our findings contribute to better understanding the behavioural underpinnings of effective ASO-parent university relationships.