Thirteen research syntheses were analyzed to determine the academic, social, and psychological effects upon learners who are gifted and talented of three grouping practices: (1) ability grouping for enrichment; (2) mixed ability cooperative grouping for regular instruction; and (3) grouping for acceleration. It was concluded that the research showed strong, consistent support for the academic effects of most forms of ability grouping for enrichment and acceleration, but that the research is scant and weak concerning the socialization and psychological adjustment effects of these practices. Claims for the academic superiority of mixed ability grouping or for whole group instructional practices were not substantiated for gifted and talented learners. Other conclusions indicated that: academic outcomes of ability grouping vary substantially from effects reported for average and low ability learners; full time, pullout, and within-class grouping can all produce substantial academic gains; and there is little impact on self-esteem and a moderate gain in attitude toward subject in full time ability grouping. A series of guidelines for practices is included. Appendices chart the meta-evaluation of the research syntheses and the research-supported conclusions concerning grouping issues. (45 references) (DB)