tzippi,
Thanks for your reply. I agree that mandating that Bais Yaakov girls wear the same plaid skirts as Catholic schoolgirls makes economic sense. But why is it considered appropriate to dress this way, when copying the fashions of a non-Jewish segment of the public would generally (as noted in multiple posts above) be considered unacceptable? This is something that has always seemed odd to me, perhaps because I never had a real school uniform (except in seminary, sort of–are students at BJJ still required to wear “blue & brown”?).