There is an extensive international research literature on the effect of ability grouping (e.g., tracking, streaming, banding, setting) on children's academic and behavioral outcomes. However, it is questionable to what extent the findings of research on this topic have influenced the practice of ability grouping in New Zealand schools. Fifteen high schools in Christchurch were surveyed regarding their policies and practices on ability grouping. Interviews focused on the types of grouping used in academic subject areas, perceived benefits and disadvantages of this grouping, and perceived consequences for average students, gifted students, students with special needs, and Maori and Pacific Island students. Reported grouping practices, and views about these, are compared with findings from the literature on ability grouping. The need for schools to adopt more evidence-based strategies for ability grouping are discussed and recommendations for practice and for further research are outlined.