The Least Developed Countries Expert Group (LEG) was established in 2001, and is mandated to provide technical guidance and support to least developed countries (LDCs) on the:

• process to formulate and implement national adaptation plans (NAPs) 
• the preparation and implementation of the national adaptation programmes of action (NAPAs)
• the implementation of the LDC work programme. 

The LEG is also mandated to provide technical guidance and advice on accessing funding from the Green Climate Fund (GCF) to support the formulation and implementation of NAPs, in collaboration with the GCF secretariat. Furthermore, the LEG is mandated to engage a wide range or organizations in implementing its work programme.

The LEG meets twice a year to develop and review progress on the implementation of its work programme through a variety of modalities including technical guidance to the countries, technical guidelines, technical papers, training activities, workshops, expert meetings, NAP Expos, case studies, capturing and sharing of experiences, best practices and lessons learned, NAP Central, monitoring of progress, effectiveness and gaps, collaboration with other bodies, programmes and organizations, and promotion of coherence and synergy.