Research has shown that employee voice (i.e., speaking up with constructive suggestions at work) can be beneficial to organizational functioning, but much less research has looked at how voice affects the individual employee. Based on the job demands-resources (JD-R) model, we develop and test theory on how voice may positively affect employees' job engagement over time. We hypothesize that voice leads to perceived voice appreciation, which serves as an important job resource that can lead to longer-term increases in job engagement. Furthermore, we propose that emotional stability, as an important personal resource, affects the indirect relationship between voice and increases in job engagement through perceived voice appreciation. We suggest that the indirect relationship becomes stronger as emotional stability increases. We tested our conditional indirect effect model using 5-wave longitudinal data from 614 employees over a period of 4 months. We applied latent growth curve modeling to predict within-person changes in job engagement. Results provided support for our hypothesized model. Overall, our findings suggest that the interplay between relevant job and personal resources affects whether and how voice can increase employee motivation over time.