After respondent filed a charge against petitioner alleging employment discrimination in violation of Title VII of the Civil Rights Act of 1964, the Equal Employment Opportunity Commission issued her a Notice of Right to Sue, which did not identify the forum in which she might sue, but did advise her that she must bring suit within 90 days. Within that period, she filed a complaint in an Illinois county court, alleging that petitioner had discriminated against her on the basis of her sex in violation of the State Human Rights Act. After petitioner filed a motion to dismiss - and outside the 90-day period - respondent moved to amend her complaint to allege that the facts already pleaded also constituted a violation of Title VII. Petitioner removed the case to the Federal District Court and moved to dismiss, contending that, because the state court lacked jurisdiction over a Title VII claim, the original filing in state court could not toll the 90-day period. The District Court rejected this contention and, after a trial on the mer