<p>Managers are said to play a vital role in supporting their employees’ mental health. However, prior research has fallen short in conceptually and operationally defining the specific ways managers can support employees experiencing poor mental health. To address this gap, six independent studies were conducted to develop and validate a behavioral measure of mental health-responsive supervision (MHRS), which describes how managers can respond supportively in such circumstances. The resulting 16-item measure captures four interrelated dimensions of MHRS, each representing a specific way in which managers can manifest their supportive response. Those four MHRS subtypes include communicating compassionately, reducing demands, giving recovery time, and promoting mental health resources. Evidence supports the measure’s discriminant, convergent, criterion, and incremental validity. Criterion validity results indicate that employees who had received more MHRS when having recently experienced poor mental health reported better mental health (more work engagement, less burnout and depression) and increased self-help behavior (using mental health resources, taking time off rather than attending work while mentally unwell). Incremental validity findings show that one or more MHRS subtypes explained unique variance in most outcome variables beyond what was accounted for by a widely used general measure of supervisory support. Implications for theory, practice, and how the MHRS measure should be used in applied and research settings are discussed.</p>