This part of the Manual aims to provide sufficient methodological advice to allow participating National Focal Centres to sample and prepare an accurate measurement of the quantity and quality of litterfall, from selected plots of the ICP Forests intensive monitoring system. Harmonization of procedures of collection and chemical analysis is essential to ensure comparability of the chemical composition of litterfall, and accurate assessment of LAI. Only data obtained by the methodologies described in this chapter will be accepted for submission into the international database of the ICP Forests programme.