We investigated factors associated with proficiency value-added in Portuguese and Mathematics to high school students in the state of Rio de Janeiro. The relevance of this work is based on the importance of this level of education for the full realization of the right to education, the low levels of performance evidenced by national educational evaluation systems and the lack of studies in Brazil on factors associated with student performance at this level of education. Following notes of the literature on effective schools and studies based on value-added analysis, we investigated the variation of proficiency gains in Portuguese Language and Mathematics among students from different schools of the network and its association with a set of internal and external factors to school. Data were obtained through the Evaluation System of education in the state of Rio de Janeiro - SAERJ. From a longitudinal approach, added-values over the high school was given by comparing the previous proficiencies students in SAERJ 2010, when they were attending the 9th grade of elementary school, and the output proficiencies of these same students, when evaluated in the 3rd year of high school, in 2013. Data analysis was developed in three stages. At first, given that our interest group was made up of students without reproaches, we compare characteristics of this group with the rest of the students evaluated by SAERJ in 2013, in order to check how much our sample approached the state of the rest, in terms of sociodemographic and socioeconomic characteristics of students as well as the characteristics of the education system (shift, high school mode, geographical distribution etc.). The results of this comparison showed that the sample of students is very similar to the universe of evaluated students. In the second step, we map the distribution of proficiency added-values between schools of the state, seeking to identify significant variances in the aggregate figures and schools that had stood out positively or negatively. The completion of this second stage allowed us to categorize the schools in the sample, with a view both their average performance and its location on the scale of SAERJ performance standards. The results show that there are major challenges in high school, for the two curriculum components evaluated, especially in Mathematics, in which a small minority of students is in the appropriate level or advanced level of proficiency. In the last step, through the use of hierarchical linear modeling, analysis of factors associated with proficiency added-values was made. The main results show that school size matters both for effectiveness and for school equity; that school failure is associated with lower performance of the students especially in mathematics; and more democratic policies and practices of school management are associated with better proficiency in Portuguese and, especially, in mathematics. The thesis also provides evidences of schools where there is a significant association between efficiency and equity, especially in Portuguese.