The Reflections series synthesizes lessons from past evaluations to support organizational learning about what works and what doesn't. This paper focuses on implementation of the Leave No One Behind principle and covers the particular features of civil society organization (CSO) status and models that may enhance or detract from their ability to reach the furthest behind and work as partners with UNDP.

It identifies eight lessons:

1. CSOs can provide essential services where public and private options are absent or limited. This support, however, rarely changes the root causes or longer-term effects of exclusion.
2. CSOs often face constraints in demanding and monitoring the fulfilment of rights for those left behind, but this function can be enhanced when international partners promote its use.
3. People at risk of being left behind often form their own community organizations, and international organizations have been encouraged to become familiar with the attributes of their informality.
4. CSOs can facilitate access to local development planning for those at risk of being left behind. Bottom-up planning is more effective when coordinated and met by top-down support and social change.
5. Enhancing CSO networks allows local and national organizations to link excluded groups to high-level advocacy and limit the negative effects of competition.
6. Tailored grant mechanisms for CSOs can be an effective way to translate international goals to local contexts.
7. Elite capture contradicts the LNOB principle, but not enough is understood about the ways to promote representative CSO governance models.
8. CSOs are often taken as a proxy when donors seek to identify those at risk of being left behind. This is a good way to reach people who face discrimination until data safeguards are advanced.