jats:titleAbstract</jats:title>jats:pStrong emergency collaboration is commonly assumed to involve a joyful passage to trust and confidence. Organizations are said to collaborate when fear and suspicion are overcome. Thus, negative, or sad, affects—such as anger, fear, disdain, despair, frustration—appear opposed to emergency collaboration. In this hybrid theoretical‐empirical paper we challenge these assumptions by elaborating the affect theories of the philosophers Gilles Deleuze and Baruch Spinoza with ethnographic research on emergency collaboration undertaken before and during the UK emergency response to COVID‐19. Moving beyond considerations of sad affects as either undermining collaboration, or as moderators of excessive trust, we explore how a range of sad affects are both prevalent and potentially beneficial within trustful emergency collaboration. Rather than celebrate such affects, our analysis contributes by drawing attention to the overlooked role of vacillations of affect between joy and sadness within emergency collaboration. In so doing our findings decentre but do not disregard the role of trustful confidence within theories and practitioner prescriptions of emergency collaboration.</jats:p>