Purpose: The purpose of this study is to examine the impact of limited English proficiency on employee performance in manufacturing companies to help explain the degree to which employers are willing to invest in ESL or other initiatives designed to overcome language barriers. Design/methodology/approach: While the primary emphasis of this study was to identify the costs associated with LEP for companies in an effort to explain their level of involvement and investment in ESL programs, it is also important to note that the results also suggest some significant costs for LEP employees too. Findings: The findings of this study provide valuable insight into why organizations are reluctant to invest in language education and training for employees. Originality/value: The quantitative nature of the study provides useful baseline data that can assist in providing evidence of the effect of LEP on performance in companies. It also provides a better understanding of where investments in education and training yield the greatest returns. (Contains 8 tables and 1 figure.)