Parental consent requirements for conducting school-based STD testing of minors vary by locality. Active consent (NO, IHS, Baltimore) requires parents to return consent forms for their child(ren) to participate. Non-response may indicate disinterest rather than opposition, and limits participation. Passive consent (NYC) requires parental response to prohibit a child's participation; therefore non-response is affirmative. Parents rarely opt-out their children, however low health literacy and language barriers are obstacles to assuring full parental understanding. Philadelphia requires only parental notification for screening. Laws ensuring confidential STD testing for minors may concern parents who support STD education/testing but want access to test results.