Although net-new account growth is a primary strategy for emerging and maturing B2B companies, successful companies reach the point at which they must devote equal or greater attention to keeping and growing existing accounts more effectively than their less successful peers. Rather than leaving account managers and partners to expand the existing customer base on their own, B2B marketers must apply go-to-market competencies to support growth through cross-selling and upselling with the same rigor they apply to new-business strategies. In this report, we define cross-selling and upselling and the role marketing should play in these activities.