This thesis consists of two central Parts. Part 1 examines the extent to which an agent s transaction-specific investments (TSIs) in a customer relationship increase his/her concerns for opportunism by his/her own co-workers. Thus, unlike prior research in marketing that examines opportunism by the recipient of TSIs, I show that agents become concerned with opportunism by non-recipients of TSIs. I then introduce novel moderators that shape the relationship between TSIs and concerns for internal opportunism. Importantly, I also show that in response to concerns for internal opportunism, agents will engage in internal safeguarding behaviors. Notably, unlike external safeguards between firms which tend to benefit firms (e.g., relational norms), I show that internal safeguarding has a deleterious effect on performance. I test the set of hypotheses with data collected from two sources: account managers and their supervisors. In Part 2, I advance the emerging view on customer solutions by simultaneously examining the networks within and between selling and buying teams involved in the development and deployment of complex customer solutions. Such a concurrent within-and-between perspective helps to bridge research on buying and selling teams, which prior research tends to examine only in isolation of each other. This research also extends the literature by showing how within-team network characteristics interact with between-team network characteristics to affect solution effectiveness. Notably, I advance the literature by moving beyond firm-level and individual-level dyads to team-level dyads and introduce a new network characteristic mirrored ties to help our understanding of the interactions between these dyads. I develop my hypotheses in the context of a sales team selling a complex customer solution to a buying team and test the hypotheses using an innovative, picture-based conjoint field experiment from 233 purchasing managers.