A significant number of science educators have recognized the importance of the history of science (HOS) in understanding the nature of science (NOS) and scientific content. However, there is little empirical evidence for this effect in the South American educational context. This article shows empirical data about the contribution of HOS in enhancing in-service biology teachers’ understanding of NOS and the effect of HOS in enhancing the understanding of evolution and NOS in high school students. The authors used the VNOS-D+ questionnaire to assess teachers’ and students’ views of NOS at the beginning and the end of interventions. The inclusion of writing artifacts such as lesson “tickets-out”, content tests, and lesson plans for teachers enriched the analysis. The students’ understanding of evolutionary theory was assessed using the ACORN questionnaire. Some of the most important results of the project are the significant improvements observed in teachers’ understanding of NOS, although they assigned different levels of importance to HOS in these improvements, and a significant effect of HOS with students’ understanding of NOS. There was no significant difference between students’ understanding of evolution in treatment and control classes. The authors make suggestions for science teacher education and future research to improve the effect of HOS on students’ and teachers’ understanding of NOS and scientific content.