The study reported here investigated experienced teachers' views on several nature of science (NOS) issues 2 to 5 years after they completed a demanding secondary science teacher education program in which the NOS was an extensive and recurring component. Both quantitative and qualitative data were collected and analyzed to determine study participants' NOS understanding. Study participant's NOS views were determined to be generally accurate and robust, suggesting that experiences in their science teacher education program had a long-lasting positive impact on NOS understanding. The preservice program that study participants completed has several unique features that may account for that long-lasting impact and has implications for preservice and inservice science teacher education professional development.