While the previous research has examined antecedents of supervisors' voice endorsement, it has generally overlooked its effects on voicers' affective and behavioral reactions, probably because of the underlying assumption that supervisors' voice endorsement is inherently beneficial and likely to encourage more proactive behaviors in the future. In this research, we offer a theoretical model of the double-edged effects of supervisors' voice endorsement on voicers' subsequent personal initiative. Drawing on cognitive appraisal theory and related research, we proposed that supervisors' voice endorsement prompts two different cognitive appraisal processes in voicers that evoke two distinct emotional experiences-feeling pride and feeling envied-with countervailing effects on voicers' subsequent personal initiative. Specifically, voice endorsement results in voicers not only feeling pride, which enhances their subsequent personal initiative, but also in their feeling envied, which reduces their later personal initiative. Moreover, we extend the cognitive appraisal theory of emotion from a social constructionist approach by incorporating coworker support-an important relational context-as a contingent factor shaping the effects of voice endorsement on feeling pride and feeling envied and on voicers' subsequent personal initiative. The results from two field studies-a weekly experience sampling study with 574 observations from 119 employees and an event-based daily experience sampling study with 787 observations from 180 employees-largely support our theoretical model. This research suggests the importance of considering the perspectives of all the stakeholders in the proactivity triad (i.e., the focal employee, the supervisor, and coworkers) in order to sustain employee proactivity. (PsycInfo Database Record (c) 2024 APA, all rights reserved).