We report results from 2 language-based processing tasks designed to investigate the performance of linguistically diverse learners. The tasks were the Competing Language Processing Task (CLPT) and Non-Word Repetition (NWR). Participants were 100 school-age children in 1 of 3 different experimental groups: monolingual English-speaking children with specific or primary language impairment (LI), typical English-only-speaking children (EO), or typical Spanish-English bilingual children (BI). On both CLPT and NWR, EO group performance was best and LI group performance was poorest, with BI group performance falling in between. Likelihood ratios indicated that performance on these tasks does not provide compelling diagnostic power for separating typically developing bilinguals from monolingual children with LI. One exception is that children who obtained an NWR score of 93 percent or higher could be ruled out of the LI group with a high degree of confidence.