The current paper details an action research approach to developing and evaluating a group cognitive-behavioural therapy (CBT) program for older adults (65+ years) experiencing depression. This approach allowed the development of a novel program and for each component of the program to be evaluated and modified in an iterative, developmental fashion – a particularly important, ethically responsive feature when working with vulnerable populations. Formative and summative evaluations allowed the identification of beneficial, cohort-specific elements of an intervention without compromising individual wellbeing. A mixed methods data design was used to triangulate multiple and repeated quantitative and qualitative measures; in essence, a formalisation of usual clinical practice. The outcomes from the pilot study will be discussed in the context of a methodology that uniquely facilitates microanalytic research while maintaining therapeutic accountability, making replication and program accountability available to all clinicians.