We've certainly had this conversation before, but thought I'd post some new commentary that I think highlights some important points when thinking about the issue. If you don't read Peter DeWitt's blog, I'd suggest it - he's pretty level-headed and practical with how he approaches topics: http://blogs.edweek.org/edweek/find..._or_mixed_grouping_a_point_of_contention.html In short, as I've advocated, it's not that we use or don't use ability groups that matter - it's how. Ability groups, like most things, can be helpful or harmful in different contexts. Ability groups with low expectations for the lower groups, and that are fixed with no acceleration/mobility between groups? Yep, pretty bad. However, ability groups can be a core functional ingredient in differentiated learning, instructional levels, zones of proximal development, etc. - basic, core characteristics of education. Those are pretty good things. As a side note, I've made this point before, but ability groups aren't really "ability" groups, which tends to refer to fixed attributes. They should really be called "skill groups," which highlights the content, rather than the innate characteristics of the learner. No doubt there are folks that are finding success without ability groups, particularly folks who aren't teaching as many basic skills, and folks with classrooms that are more homogeneous in instructional level of students. However, simply pointing to an effect size of ability grouping without considering what that research is actually describing, then writing off the entire concept of differentiated instruction in group format, is pretty reckless.