With the aim of extending the healthy physiological variability thesis to Leadership Studies, we examined the hypothesized links among leaders' within-person variability in physiological arousal, their task- and relations-oriented behaviors and their overall effectiveness. During regularly-held staff meetings, wristband skin sensors and video cameras captured synchronized physiological and fine-grained behavioral data of 36 leaders within one organization. Perceived leader effectiveness ratings were obtained from their followers. Multi-level log-linear analyses showed no elevated levels of arousal during the task-oriented behaviors of both the highly effective and the less effective leaders. The highly effective leaders showed a significantly greater likelihood of high levels of physiological arousal during positive and negative relations-oriented behaviors. We thus report a physiological correlate of relations-oriented leader behavior; especially among the most effective leaders, higher levels of arousal co-occurred with their positive and negative relations-oriented behavior in the meetings. Having used two high-resolution methods to advance insights about effective organizational leadership, this field study illuminates the importance of capturing the co-occurrence of within-person variability in leaders' bodily responses and their precisely measured behaviors over time in a functional social setting at work.