Institutional reform or development happens when those within the organisation want that development and are willing to commit the time, effort and necessary resources under their control to support it. This may be referred to as the will for development. Over the years, a general strategy for legislative development has emerged in which the will for development is enlisted in one or more of three ways: mapping, incentivising, and creating demand. These efforts focus on identifying the will for development independent of the legislative strengthening project itself. This paper will explore how success in supporting the budget process by the United States Agency for International Development-funded Afghanistan Parliamentary Assistance Programme enhanced and/or created the will for further development within that legislature. The paper will demonstrate how budget process support can be used to engage a broader constituency of committees and civil society organisations, creating a self-sustaining reform dynamic to be referred to as the demand dynamic.