As a yearlong exploration of air quality and its relation to respiratory health, the "Air Toxics Under the Big Sky" program offers opportunities for students to learn and apply science process skills through self-designed inquiry-based research projects conducted within their communities. The program follows a systematic scope and sequence designed to first lay a strong foundation, followed by activities intended to expand understanding, and ending with a final step aimed at achieving retention of content and principles learned. The foundation consists of content regarding environmental health sciences and human health. The next level guides students during their independent study projects as they test their hypotheses, analyze results, and draw conclusions. The final step requires these junior researchers to share their findings with others in some type of culminating event, with the most prominent being a high school symposium held at the conclusion of the school year. This article describes the evolution of the Air Toxics Under the Big Sky program since its inception in 2003. (Contains 2 notes.)