This chapter provides a theoretical model to explain the heterogeneity of family businesses regarding sustainability activities. Family business scholars tend to argue that the non-financial goals of family businesses, through the construct of socio-emotional wealth (SEW), would motivate a family business to adopt more a proactive sustainability strategy than a non-family business that is driven by the financial goal. However, studies have mixed supports when scholars rarely consider that family businesses have both financial and non-financial goals and their importance are contingent upon the life-stage of the firm. In this chapter, I propose a temporal framework that differentiates family businesses at three stages—founding, post-founder, and cousin consortia—in which the alignment between financial and SEW goals varies, and thus changes the focus of a family business’ sustainability strategy. It discusses critical role of temporal factor when examining sustainability strategies of family businesses.