Mental health issues are extremely common in the developed world, with as many as one in five people experiencing a mental illness every year. There are a host of negative outcomes for both organizations and individuals with mental health problems. One strategy that previous research has shown to be effective in reducing stigma around mental illness in organizations is mental health awareness training (MHAT) for leaders. The aim of the current study was to evaluate a complementary program to the MHAT, the Coworker Health Awareness Training Program (CHAT) for employees. The present study uses a wait‐list control design (N = 40) to test the effectiveness of the CHAT on various outcomes, such as knowledge, stigma, self‐efficacy in recognizing and addressing mental health problems, mental health promotion intentions, and willingness to use resources. Results showed that those employees who were trained with the CHAT displayed increases in knowledge, self‐efficacy, mental health promotion, and willingness to use resources. These results provide support for the effectiveness of the CHAT, and have practical and methodological implications.