RESUMEN Introduccion: La educacion para la sexualidad hace parte del compromiso de formacion integral de las instituciones educativas en Colombia; por eso evaluar caracteristicas de estos procesos educativos y buscar asociacion con cambios en conocimientos, actitudes y practicas en adolescentes y jovenes, aporta informacion para reorientar y enriquecer estrategias y programas en este campo. Metodologia: Estudio observacional de corte longitudinal analitico en adolescentes y jovenes entre 12 y 19 anos quienes recibieron un proceso de educacion para la sexualidad y tres mediciones de conocimientos, actitudesy practicas mediante encuesta, previo consentimiento informado. La ultima medicion se hizo dos anos despues del proceso educativo inicial. En el analisis se busco la asociacion de variables mediante coeficiente de correlacion de Spearman, la t de Student o chi cuadrado dependiendo del tipo y caracteristicas de las variables. Resultados: Grupos de 244, 111 y 139 estudiantes participaron en las mediciones. En conocimientos se encontro diferencia significativa por sexo a favor de las mujeres y mejores conocimientos en el grupo que ha tenido relaciones sexuales, en tanto que las actitudes fueron mejores entre quienes no las han tenido; asi mismo se encontro correlacion entre actitudes y practicas. Las tecnicas didacticas con significancia estadistica fueron el cine-foro para conocimientos y el taller para actitudes. Y como agente educativo solo mostro diferencia el personal de bienestar estudiantil para trabajar las actitudes. Conclusiones: Es necesario continuar desarrollando investigacion sobre los procesos de educacion para la sexualidad, pues la efectividad del trabajo educativo observado en la persistencia e integralidad de cambiosen conocimientos, actitudes y practicas aun deja muchos interrogantes. Salud UIS 2012; 44 (2): 21-33 Palabras clave: Sexualidad, Adolescente, Conocimientos, Actitudes y Practica en Salud, instituciones academicas. ABSTRACT Introduction: The education for sexuality is part of the commitment to integral formation made by educative institutions in Colombia; therefore, the evaluation of these features of the educative processes and the search of association with changes in knowledge, attitudes and practices among adolescents and youngsters provide information to guide and enrich strategies and programs in this field. Methodology: Observational and analytical longitudinal study among adolescents and youngsters with age between 12 and 19 years who received an educational process for sexuality and three measures tests of their knowledge, attitudes and practices were taken throughout a inquest, with a previous informed consent. The last measurement was done two years later from the initial educative process. In the analysis the association of variables was sought out using the Spearman correlation coefficient, the Student’s T distribution or chi squared test depending on the type and characteristics of the variables. Results: groups of 244, 111 and 139 students participated in the measuring. In terms of their knowledge a significant difference was found between genders favoring women and the group who has had sexual intercourse; in contrast, the attitudes were best between those who have not had it. Likewise, it was found that there was a correlation between attitudes and practices. The didactic techniques with a statistical significance were the movie forum for knowledge and the workshop for attitudes. As educative agent the students welfare staff was the only that showed a difference when working with attitudes. Conclusions: Since the effectiveness of the educative training observed in the persistence and integrality of changes in knowledge, attitudes and practices still leaves many questions, it is necessary to continue the development of research about the processes of education for sexuality. Salud UIS 2012; 44 (2): 21-33 Key words : Adolescence, sexuality, Health Knowledge, Attitudes, Practice, Schools.