Abstract Objectives To identify the impact of birth weight on the development of metalinguistic skills and performance in reading, writing, and arithmetic in students aged 6 to 10 years, enrolled from the 1st to the 4th grade of Elementary School in public schools of the metropolitan region of São Paulo. Methods The concurrent cohort included 315 students. Birth weight was the exposure variable, and the outcomes were performance in receptive and expressive language, oral metalinguistic skills, and performance in writing, arithmetic, and reading. The tools employed were the Test of Language Competence (TLC) and the School Performance Test (SPT). Students were grouped into quartiles by birth weight for data analysis (P1: < 2170 g, P2: from 2171 g to 2450 g, P3: from 2451 g to 3150 g, and P4: > 3150 g). Results The authors observed a tendency for the lower performance of the two groups with lower birth weights in listening comprehension and oral expression. The lower-weight group tended to perform poorly compared to the other groups vis-à-vis reading. In the global result of the SPT, worse performance was observed in the students in the first quartile compared to the others (p= 0.019). The multivariate analysis revealed no association between birth weight and results in the tests applied after adjusting for maternal schooling. Conclusions Birth weight can interfere with oral and written language development. However, the determination of these processes occurs in the face of complex interaction that includes sociodemographic factors, especially family support and maternal schooling.