The aims of this study are to assess L1 and L2 variables that influence the reading acquisition of students of Moroccan origin in the South of Spain and compare their reading ability with native Spanish-speaking children. Participants were 38 students of Moroccan origin and 37 native Spanish-speaking students from the same classes. We used an oral vocabulary test and a reading comprehension test, which taps lexical, semantic, and syntactic reading processes, and reading fluency. The results indicated that immigrant students differed from native Spanish-speaking students in word reading, reading fluency, and the use of punctuation marks, but there were no significant differences in reading comprehension. In native Spanish-speaking students, reading comprehension correlated significantly with oral vocabulary and the other reading processes, but in the students of Moroccan origin, only receptive oral vocabulary in L2 correlated with the use of punctuation marks. Being in schools with educational resources specifically aimed at helping the Moroccan pupils was associated with a higher level of word reading in immigrant students.