The partnership model is ubiquitous in sustainability. This chapter argues that the partnership debate's focus on sectoral factions disregards other aspects of diversity and their potential to affect partner relations and partnership effectiveness. It identifies aspects of partner diversity that are understudied but consequential, and considers their effects on pathways to partnership effectiveness. Governance mechanisms are theorized to contribute significantly to the performance of all organizations. As the most noteworthy mechanism of corporate governance, boards are considered to affect a firm's performance as measured by financial success, market share or investor satisfaction. Faultlines are hypothetical dividing lines splitting board members into sub-groups based on the analysis of several intersecting attributes.