A field survey of 180 municipal government office employees (82% women, 21-75 years old) investigated the potential moderating effects of internal health locus of control (HLOC) and self-efficacy on employees' reactions to ergonomic job design. Internal HLOC moderated the associations between ergonomic job design and somatic complaints and turnover intentions, and, to a lesser extent, job satisfaction. Self-efficacy moderated the associations between job design and job satisfaction, somatic complaints, and, to a lesser extent, persistent pain. Employees with low self-efficacy or low internal HLOC were influenced more by their physical job conditions than those with high self-efficacy or high internal HLOC. Implications for the ergonomic design of offices are discussed.