<strong>Background:</strong> Mental health care is undergoing rapid digital transformation, with continued development and implementation of digitally delivered interventions. Despite growing evidence for digital mental health interventions, implementation in routine practice has often lagged technological advances. Although teletherapy became more widely accepted during the COVID-19 pandemic, little is known about the psychological processes through which clinicians adapt to disruptive changes in treatment delivery when required to work within a novel medium. <strong>Objective:</strong> This study explored how therapists who had not previously adopted teletherapy interpreted and adapted to its enforced uptake during the COVID-19 pandemic, with particular attention to changes in expectations, perceptions of the therapeutic alliance, and professional practice. <strong>Methods:</strong> Six UK-based accredited clinical psychologists, none of whom had previously practiced video-based teletherapy, participated in semistructured interviews conducted between May and July 2021, following the rapid shift toward remote delivery. Data were analyzed using reflexive thematic analysis to explore therapists’ experiences of adaptation, belief revision, and therapeutic interactions. <strong>Results:</strong> We identified the following four themes: (1) revision of anticipatory beliefs, (2) context-medium differentiation, (3) medium affordances, and (4) relational viability and selective integration. Therapists began practicing teletherapy with concerns about accessibility, safety, therapeutic techniques, and relational quality. With sustained practice, clinicians revised many of their assumptions. Therapists also distinguished difficulties associated with implementation contexts from perceived properties of teletherapy itself. They described adapting clinical procedures and techniques, recognizing both constraints and affordances of the medium, and developing more differentiated views of when teletherapy was appropriate. Clinicians generally found teletherapy to be an acceptable therapeutic medium, but not equivalent to in-person practice. <strong>Conclusions:</strong> Adapting to teletherapy involved more than accepting a new tool. It required therapists to reconsider assumptions about therapeutic interaction, safety, and conditions needed to sustain an effective therapeutic relationship. The findings suggest an experience-based professional adaptation process in which initial assumptions became differentiated through sustained use. While these findings support teletherapy uptake specifically, they may also inform how clinicians evaluate other digital mental health technologies, while recognizing that changes to the communication medium are not equivalent to changes in the therapeutic process or agent.
