© 2022 Wiley Periodicals LLC.Research indicates that relationship-oriented HR practices can increase organizational knowledge, yet we know little about the effects of relationship-oriented HR practices on employee knowledge management behaviors. Drawing from affective events theory, we examine the indirect effect of participation in one type of relationship-oriented HR practice (i.e., organizational social activities) on three knowledge management behaviors (i.e., knowledge sharing, knowledge hiding, and knowledge manipulating) via positive affect, as well as the conditional indirect effect of intrinsic motivation for organizational social activities on these relationships. Utilizing a time-separated field study (n = 163), our analysis reveals positive affect fully mediates the relationship between participation in organizational social activities and (a) knowledge sharing and (b) knowledge hiding, and partially mediates the relationship between participation in organizational social activities, and (c) knowledge manipulating. Most interestingly, we unexpectedly found a positive direct effect of participation in organizational social activities on knowledge manipulation, even though the indirect effect via positive affect was negative. The results also indicate that, for individuals with high intrinsic motivation for social activities, there is a significant indirect effect of participation in organizational social activities on all three knowledge management behaviors.