Language is an important marker of identity. Guided by social identity theory and using a grounded theory approach, this study examined how languages are chosen and shape experiences in the workplace. Results suggest that language use is influenced by both external (norms, business needs) and internal (identity, language comfort) processes. Furthermore, speaking Spanish in the workplace has both positive (inclusion, camaraderie) and negative effects (exclusion, harassment, discrimination), with many more negative effects reported by our participants. Speaking Spanish appears to mark the speaker as an outsider. Together, our results indicate that language use is an important choice, personally and professionally, for employees and plays an important role in the way individuals are treated in the workplace. (Contains 5 notes.)