Gender differences in achievement The case of Chile In 2005 the chilean evaluation system (SIMCE) decided to analyze the gender differences of our student's performance in several assessments (SIMCE, PISA, TIMSS and CIVICS) . Some of the research questions were is there any difference between the achievement of females and males in Spanish (reading and writing), Math, Science o Social studies?, is the gap between females and males changing over a certain period of time (2000-2004)?, is there any difference in the gender gap between the students of 4th, 8th and 10th grade? The most important conclusions that we obtained are summarized in the following ideas: in the national assessment, females consistently outperformed males in reading and writing. This is persistent in the students from different social backgrounds, specially in students from higher socioeconomic levels. As the PISA results shows, chilean females seems to have a better attitude towards Reading than males and also a better performance than males. In SIMCE 2004-8th grade, males outperformed females in Math, Science and Social Studies. The results from TIMSS 2002 showed that males outperformed females in Math and Science. Is very interesting to observe that results from PISA 2001, were students were faced tasks related to real life, using knowledge and skills, females and males had similar performance in this two areas. Nevertheless, in Reading females outperformed males. As the evidence found in TIMSS, the gap between females and males gets wider between 4th and 8th grade than in the higher levels. This paper was prepared by SIMCE, Ministry of Education, Chile.Carolina Valenzuela (33), sociologist from the Catholic University of Chile, master in sociology. I worked 4 years in the international assessments team (in charge of PISA, TIMSS and CIVICS), and since 2006 I coordinate the Data Analysis team, in charge of analyzing the students results from the national assessment and the international ones. Since 2001 I work in the national evaluation system (SIMCE), in the Ministry of Education Chilean Ministry of Education Ms.carolina.valenzuela@mineduc.cl