Reading comprehension in bilingual children depends on the extent to which each language is used in daily life. To date, most bilingual studies have focused on children who learn the majority language as their second language (L2 bilingual children). In contrast, bilingual children learning the majority language as their first language (L1 bilingual children) have rarely been addressed. To bridge this gap, this study explored (a) mean differences in reading comprehension and its preschool predictors as well as (b) differential associations between these variables for children from different language groups. The study included 1,842 monolingual, 269 L1 bilingual, and 237 L2 bilingual children from the German National Educational Panel Study who were assessed on their reading comprehension in grade 4 of elementary school. Preschool predictors of reading included linguistic abilities and phonological processing skills that were obtained in kindergarten. The results indicate that after accounting for the children's socioeconomic background, L2 bilingual children exhibited lower reading comprehension and linguistic skills than L1 bilingual children, who in turn were outperformed by monolingual children. In contrast, phonological processing skills were comparable across groups. Furthermore, the three language groups presented similar relationships between reading comprehension and its preschool predictors.