This study investigated the impact of second language (L2) lexical quality on L2 reading comprehension in bilingual primary education. The participating children were taught in the L2 English for 30-50% of the time and the remaining time in their L1 Dutch. Seventy-three pupils from four different schools were assessed in the L2 on vocabulary, lexical specificity and phonological awareness in kindergarten, vocabulary, lexical specificity and decoding in grade 1, and reading comprehension in grade 3. L1 reading comprehension was tested in grade 2. Results showed that lexical specificity in kindergarten had a direct effect on L2 reading comprehension in grade 3, and phonological awareness in kindergarten had an indirect effect on L2 reading comprehension via L2 decoding skills in grade 1. These effects remained significant after taking L1 reading comprehension skills in grade 2 into account. The lexical specificity task, measuring specificity of phonological representations, had a more profound impact on reading comprehension than vocabulary. This highlights the importance of examining the specificity of phonological representations when it comes to studying L2 reading comprehension proficiency and implies that teachers should focus on L2 lexical specificity in bilingual kindergarten to build the foundation for L2 reading comprehension in grade 3.