Cultural-historical activity theory (CHAT), founded on the seminal work of Vygotsky and evolving in the subsequent work of Leont'ev and Engestrom, continues to emerge as a robust and increasingly widely used conceptual framework for the research and analysis of the complex social mediation of human learning and development. Yet there remains ongoing methodological ambiguity around its use in qualitative research and therefore questions regarding its effectiveness in fulfilling its intrinsic interventionist aspiration. Meta-level research suggests that the primary methodology theorised for CHAT-Engestrom's development work research that is based on a highly localised developmental ethnography--is not in widespread application in CHAT-based research. Instead, the majority of research employs an eclectic array of qualitative and quantitative methodologies and uses CHAT more as a heuristic device rather than engaging its more authentic interventionist motive. Given this, it is perhaps surprising there has been limited conceptualising around the prospective relationship between CHAT and action research, which remains largely under-developed. This paper argues that action research may offer CHAT a legitimate and viable complementary interventionist methodology to investigate the increasingly complex environments of social activity, particularly given escalating expectations of more democratic and participatory modes of research engagement and social learning. (Contains 1 note and 1 table.)