Organization-bounded online communities compete as well as collaborate regarding valued member resources. Membership overlap creates competition amongst communities because their overlapping members must choose where to allocate their limited time. But members also collaborate across communities in inter-community discussion threads to tackle common problems together. This paper examines how membership overlap across communities and inter-community collaboration individually and jointly affect community responsiveness, or the level of participation in a discussion thread. We analyzed a panel data of 155 online communities internal to a global company with 2,103 community-month observations. Preliminary findings show that communities with low membership overlap enjoy higher responsiveness than communities with many overlapping members, but the latter communities can significantly improve responsiveness by seeking broad inter-community collaboration on shared threads. We explain community responsiveness by the participants' desire to maintain an optimal balance between the need to be similar and the need to be different.