A recent  study by the Seattle Post-Intelligencer sheds new light on the "race gap" in school discipline (see the article). The report suggests:
1. A measurable portion of the gap is due to differences in social environment (parenting, poverty, etc.). Originally, suggestions that black kids act up more than white kids were dismissed as racist. This study confirms that a race-blind, socially created "behavior gap" accounts for some of the "discipline gap."
2. Some portion of the gap is due to strictly racial (but not clearly genetic) differences in behavior. For example, some black kids curse in school as a way of fitting in and showing that they're not "white." This factor also represents a "behavior gap" on the part of kids rather than racism on the part of school employees.
3. Some portion of the gap is due to the white establishment treating behaviors common among blacks more seriously than they need to. An example given is play-fighting, which is more common among black kids. If administrators and teachers enforce rules against play-fighting without racial bias, they nevertheless wind up disciplining more black kids as a result. This is like the needlessly harsh laws against crack, which fall unfairly on blacks even when enforced without bias.
4. Undoubtedly, some portion of the gap is due to prejudice on the part of school employees. The report is unable to measure how much is due to such prejudice.
When the study factored out some (but not all) of the social factors that lead to more misbehavior by blacks, black kids were still disciplined at almost twice the rate of nonblack students. It remains uncertain how much of that discrepancy is due to unmeasured factors (such as parents' age and education), how much is due to black kids acting up more, how much is due to unintentionally but effectively racist standards of behavior, and how much is due to teachers and administrators treating black kids worse than they treat nonblack kids.
Perhaps this study and the discussion that surrounds it will get liberals to stop expecting schools to eliminate the discipline gap any time soon. It can be reduced, but it can't be eliminated until blacks enjoy average levels of wealth, health, and education.
Here's what I said on this topic in October 2001:
A recent development in race relations in Seattle is the statistic that black schoolkids get expelled at three times the average rate. Leaders in the black community say that this discrepancy results from school officials being too hard on black kids. The suggestion that black kids might break school rules at a higher rate than average is labelled racist.
My sense is that teachers and administrators are unfair to black kids, but that black kids also break the rules more often. These two factors together are responsible for the discrepancy in discipline.
It's not that black kids break the rules more often because they're different genetically from whites, it's that they're different socially (in wealth, health, and education).
As with the gap in student performance, a primarily social difference is misinterpreted as primarily a racial one.