Using classical and quantile regression analyses, we investigated whether predictor variables for early reading comprehension differed depending on language background and ability level in a mixed group of 161 monolingual (L1) and bilingual (L2) children in second grade (6--8 years). Although L2 readers scored lower on oral language skills and reading comprehension, the prediction of reading comprehension was similar for L1 and L2 readers. Classical regression identified decoding, vocabulary, and morphosyntactic knowledge as unique predictors with no interaction with language background. Quantile regression demonstrated that the prediction of reading comprehension differed across ability levels; decoding and morphosyntactic knowledge were consistently unique predictors, but vocabulary was uniquely related only for poor comprehenders and working memory only for good comprehenders. In both types of analysis, language background did not explain unique variance, indicating that individual differences in the predictor variables explained the L1-L2 performance gap in early reading comprehension across the ability range.