A historically rich teaching intervention was developed for biological evolution with the intent of promoting a conceptual change from students' initial understanding to a more Darwinian understanding. The intervention was delivered in a small group setting to underprepared, entry–level biology students. Evaluation of the treatment, using pre–post testing, was used to document the general effectiveness of the intervention and specific changes in students' conceptions of evolution. Results indicate the use of historical materials in conjunction with a conceptual change strategy to be promising. Specific strengths and weaknesses in specific areas of biological evolution are documented. © 1995 John Wiley & Sons. Inc.