Difficulties in second language (L2) learning are often associated with recognizable learning difficulties in native language (L1), such as in dyslexia. However, some individuals have low L2 proficiency but intact L1 reading skills. These L2 learners experience frequent tip-of-the-tongue states while naming in L1, which indicates that they have a weakness in retrieval of phonological codes of words. The authors hypothesized that if naming ability is shared across languages, this difficulty would reemerge in L2 naming, which was tested using the tip-of-the-tongue experimental paradigm. Consistent with this hypothesis, low-proficiency L2 learners (n = 15) reported more tip-of-the-tongue states, more frequently mispronounced correctly retrieved words, and benefited less from phonological cuing compared to high-proficiency L2 learners (n = 23). It is notable that low-proficiency L2 learners performed worse than individuals with dyslexia (n = 16) on some of these measures, despite the same level of L2 proficiency. These results indicate that L2 naming difficulties of low-proficiency L2 learners are a manifestation not merely of their low L2 proficiency but rather of a general weakness in phonological word form retrieval, which is shared across languages. More broadly, the study provides further evidence for the existence of a distinct profile of cognitive weaknesses characteristic of the behavioral phenotype of low-proficiency L2 learners.