AbstractPrevious research has predominantly examined either voice quantity or quality. We know little about the potential tradeoff between voice quantity and quality and the role of leaders in this tradeoff. This study focused on the dual aspects of voice, examining how and when the same leader attribute facilitates (inhibits) one aspect of voice, but does not facilitate (inhibit) or even hamper (facilitate) the other aspect. Specifically, we proposed that leader critical thinking stimulates the formation of employees' implicit voice theory of the need for solid data or solutions (IVT‐SDS) before one speaks up. This belief boosts the quality of employee voice especially when voice efficacy is high, but increases the frequency of employee silence especially when voice efficacy is low. In Study 1a, we experimentally tested the relationship between leader critical thinking and employees' IVT‐SDS. In Study 1b, we experimentally examined the interactive effect of employees' IVT‐SDS and their voice efficacy on both their voice quality and silence frequency. In Study 2, a multilevel, multi‐wave and multi‐source field study, we tested the entire research model. The results supported our hypotheses. We extend the research on leadership and voice by revealing a potential tradeoff between voice quality and quantity.