This paper presents findings of a project aimed to improve the quality of science education in Southeast Mexico by the creation of a community of practice among scientists, researchers and teachers, involved in the design, implementation and evaluation of a professional development program for mathematics, chemistry, biology and physics secondary school teachers. Based on the results from an assessment of teacher competencies, a professional development program was designed and implemented for improving the preparation of science educators from public secondary schools. The program involved a collaborative effort from chemists and physicists from the Center for Advanced Research of the Politecnico Nacional, biologists, mathematicians and educational researchers from a public university, and personnel from the State Department of Education.