Organizational leaders can make a large, positive impact on their employees during crises. However, existing research demonstrates that social support is not always effective in helping employees cope with stress, and existing research has not fully identified features of support attempts that determine their effectiveness. Using mixed methods, the authors investigate the efficacy of organizational leaders' support efforts during a crisis. In the first study, 571 employees (196 university administrative staff, 192 licensed nurses, and 183 licensed engineers) described actions their leaders engaged in to support them during a global pandemic. Nine themes differentiated helpful from unhelpful leadership support: autonomy, changes, communication, personal resources, safety, timing, tone, work equipment, and workload. Study 2 used a quantitative methodology (162 licensed nurses and 239 licensed engineers) to demonstrate that leadership actions employees deemed as helpful in Study 1 were associated with less employee burnout and fewer physical symptoms. Drawing from emerging social support literature and the stressor-strain model, the findings inform optimal leadership support practices during crises.