Understanding how intelligence operates in groups is increasingly important as teamwork becomes foundational in education and work. This exploratory analysis pools secondary data from 190 unique groups (2–5 members) across four quasi-experiments investigating performance on multi-subtest group IQ batteries. These datasets included linguistic, cultural, visuospatial, reasoning, memory, and creative tasks. Across the pooled sample, exploratory and confirmatory factor analyses consistently yielded a robust two-factor structure corresponding to collective fluid intelligence (cFluid) and collective crystallised intelligence (cCrystal). This provides one of the first systematic tests of the Cattell fluid–crystal distinction at the group level, demonstrating that distributed cognitive systems may exhibit the same psychometric differentiation long established for individuals.

A second contribution emerges from examining group language composition and its interaction with the cFluid–cCrystal factors. Groups varied substantially in their proportion of members whose main language was English, enabling tests of how conversational and task-language alignment shape collective cognition. Across studies, the proportion of English-main-language members strongly predicted cCrystal performance, particularly on language and culturally loaded reasoning items. In contrast, language proportion showed only weak associations with cFluid, where tasks emphasised pattern recognition, spatial reasoning, and novel problem-solving. Moreover, English-main-language members more readily engaged in conversation compared to language-minority members, suggesting reduced involvement in communication that supports collective problem-solving. These findings indicate a double disadvantage for language-minority members in group assessments: (1) a task-language disadvantage, where culturally or linguistically loaded items reduce accessibility; and (2) a group-discourse disadvantage, where reduced conversational participation constrains the group’s ability to pool distributed knowledge.

Implications are substantial for theories of intelligence, the measurement of collective cognition, and the design of multicultural teamwork and assessment environments. Results suggest that group intelligence is not merely a reflection of member ability, but an emergent property sensitive to linguistic alignment, communicative access, and task affordances.