Bilingual staff are often used to interpret, without any assessment of their skills. In a recent study, a total of 840 dual-role staff interpreters were tested for Spanish (75%), Chinese (12%), and Russian (5%) language competence. Two percent did not pass, 21% passed at basic level, 77% passed at medical interpreter level. Staff that passed at the basic level was prone to interpretation errors, including omissions and word confusion. Thus, about 1 in 5 dual-role staff interpreters at a large health care organization had insufficient bilingual skills to serve as interpreters in a medical encounter. Health care organizations that depend on dual-role staff interpreters should consider assessing staff English and second language skills.