<p>Online collaborative learning depends on groups’ capacity to enact socially shared regulation of learning. Yet many self-report measures are fragmented, decontextualised, and misaligned with the collective unit of analysis. This study introduces a context-sensitive, task-anchored instrument with group-referenced (“we/our”) items, developed through literature synthesis, expert review, and deployment in two authentic, eight-week online collaborative projects among undergraduate pre-service teachers (academic writing; instructional design). Items are group-referenced and tied to a specific, recently completed online collaborative project so that individual respondents report on the shared regulatory processes of their own group across the project lifecycle, strengthening ecological validity and alignment with theory. A multi-stage validation process supported a four-dimension structure—Socioemotional Monitoring and Control, Goal Setting and Planning, Cognitive Monitoring, and Reflection and Evaluation—integrating cognitive and socioemotional regulation within a single measure. Initial evidence from two independent cohorts of undergraduate pre-service teachers in online collaborative learning contexts indicates reliability, conceptual coherence, and preliminary suitability for technology-rich course settings. To prevent the longer socioemotional dimension from artificially overweighting composite scores in applied settings, researchers and educators are explicitly advised to compute subscale mean scores rather than summed totals. The resulting 26-item scale offers a practical diagnostic for identifying strengths and needs in group regulation and a robust outcome for evaluating and improving online collaborative learning designs.</p>