As an example of design-based research, this study refined an assessment strategy for simultaneously enhancing inquiry-based learning and supporting achievement on conventional assessment measures. "Astronomy Village[R]: Investigating the Universe[TM]" is a software program designed to engage secondary science students in authentic and inquiry-based learning over core topics in astronomy. The software was enhanced with a 20-hour curriculum and three levels of assessment to ensure successful inquiry experiences "and" high-stakes achievement. The first year implementation of Astronomy Village[R] yielded significant gains on a curriculum-oriented exam but not a standards-oriented test, and provided useful design insights that were integrated into the second year implementations. Significant gains were obtained on the test during the second year as well. It is expected that many existing inquiry-oriented science curricula might be similarly enhanced, and is suggested that a large-scale effort to do so might have a lasting impact on science education.