The United Nations reforms initiated by Secretary General Kofi Annan have led to a wide-reaching overhaul of UN systems. One of the commitments under these reforms is to enhance the overall effectiveness of UN agencies by increasing joint programming and pooling their resources.
In practice this means that at least two UN agencies work together with one or more national partner to deliver one project. A single project document with a common workplan and budget clarifies the roles and responsibilities of all partners in the joint project.

Joint programming not only makes it easier to work with the agencies of the United Nations, but it also decreases transaction costs, avoids duplication, and increases the impact of development projects and of development support in general. Joint projects also help the UN system to support the achievement of national development goals more coherently, effectively and efficiently.

The United Nations Development Assistance Framework (UNDAF) is the principal programming tool for UN agencies to work together on country level.

The UNDAF identifies the key development priorities to be addressed by UN agencies and harmonizes their respective contributions in achieving them. It is therefore an important tool for helping UN agencies identify possible joint initiatives and programmes and avoiding duplication of effort.

Overall, the most important consideration in joint programming is the value that will be added in employing such an approach to development programming.