Introduction. Students' academic performance can be influenced by several of their contextual and personal factors. In some cases, it is influenced by the educational practices of their family of origin, and by parental support with homework and learning at home. Or in other cases, it is influenced by the characteristics of the students, as well as by their intellectual aptitudes. The aim of this study was to obtain an explicative model of relationships between contextual variables (students' perception of family support, and parents' self-evaluation of support provided to their children), students' intellectual aptitudes, parents' educational level, and academic achievement in reading comprehension upon completing elementary school. Method. The participants were 362 sixth graders from rural, indigenous private and public schools in Sonora and Morelos, Mexico. The study was conducted during the 2015 academic year. Parents' support for their children's learning at home was evaluated by versions of the Family Support Perception Questionnaire (FSPQ), one for the parents and another for students. The FSPQ evaluated four dimensions of parental support: 1. Homework Help /Reviewing, 2. Communication with school/Participation, 3. Conditions and Resources for studying at home, and 4. Monitor-ing/Communication with teachers. For assessment of academic performance in Reading Comprehension an instrument attached to the curriculum for the sixth-grade of elementary school was used, with 17 items evaluating five dimensions: 1. Identifying spelling errors in five short texts, 2. Inferring implicit information and understanding metaphors from narrative texts and short stories, 3. Recognizing figurative language in poetry, 4. Inferring the meaning of words in the dominant indigenous language, and 5. Identifying sections of a newspaper. Intellectual aptitudes were measured using reduced versions of two scales of the Screening Assessment for Gifted Elementary and Middle School Students (SAGES-2), validated for a Mexican context: 1. Thirteen items for the Language, Literature and Social Studies scale, and 17 items for the General Reasoning scale. Results. The results of a structural regression model with the EQS 6.4 program, showed that reading performance was explained mainly and significantly by the students' intellectual aptitudes, and secondly, by parents' support (as reported by parents themselves). However, family support as perceived by the students had no significant effects on reading performance. On the other hand, the parents' education level showed a significant direct effect on students' intellectual abilities, and an indirect effect on students' academic performance in reading comprehension. Discussion and Conclusion. The results show that the intellectual aptitude of the students is presented as a better predictor of their performance in reading comprehension than the variables of family support. One possible reason is that the Language Arts/Social Science subscale of SAGES-2 is probably highly associated with curricular content and learning related to reading comprehension. However, it is important to highlight the effect of two variables in the family context. First, selfperceived parental support had a positive effect, although less so, on student performance. The second aspect is that the parents' level of schooling had a significant effect on the intellectual skills assessed here.