At the international level, committees have been established within LES to gather and collate information of relevance to members' interests, to disseminate this to members by various means and support their ongoing professional development, to provide interfaces for the membership with significant external organisations, and to make recommendations where relevant to the Executive Committee and the International Delegates for the efficient management of operations. Thus LESI may be said to have a matrix organisation; along one axis are the National or Regional Societies of LES , and along the other are the various committees of LESI, which draw their membership from these societies. The committees have various tasks and functions covering Professional, Industry Sector Management, External Relations and Operations.

To perform their tasks, all committees draw upon and integrate the knowledge and expertise of individuals within the LES societies, wherever these may be found. Many of the committees are standing, as set out in the LESI Constitution , but others may be set up by the Delegates' Meeting on an ad hoc basis, either to perform a time-limited task, or as a prelude to more permanent status. The LESI committees meet formally only twice per year, as do the International Delegates from the societies. But not all committee members can be expected to attend these meetings, and a great deal of the committee work is done by correspondence and telecommunications during the rest of the year.