Sustainability is the theme of this guide: how to ensure that what starts as an initiative to build an effective principal pipeline becomes a system with the staying power to function well and produce benefits for years to come. Sustaining a pipeline requires attending to the following six elements--as defined by the authors based on research and practitioners' ideas--and this guide offers a framework for addressing them through self-study and planning: (1) Financial planning; (2) Partnerships; (3) Stakeholder involvement; (4) District policies and procedures; (5) Continuous improvement and evaluation; and (6) Communications. The guide describes each element and suggests discussion questions and local evidence for district teams to consider in assessing how well their district is currently addressing the element. A template at the end of the guide allows districts to identify sustainability elements they want to strengthen and to make a plan for the sustainability work they want to prioritize. The guide also includes a financial planning template that districts can use to account for the "soft" and "hard" funding sources available to support both the one-time and ongoing costs of the pipeline. That template also guides districts in assessing their pipeline's vulnerability to financial trouble based on the district's financial plan.