The Rural-Urban Classification categorises a range of statistical and administrative units on the basis of physical settlement and related characteristics. This document is concerned with that part of the classification which categorises certain small statistical units in accordance with a two-dimensional typology based on settlement form and settlement context. This is referred to as ‘the Rural Urban Classification for small area geographies’ or RUC for short and is concerned with Output Areas (OAs) - the smallest areas for which data are available from the 2001 and 2011 Censuses- together with agglomerations of OAs referred to as Super Output Areas (SOAs) defined at two geographic levels: Lower Layer Super Output Areas (LSOAs) and Middle Layer Super-Output Areas (MSOAs). That part of the classification concerned with higher level geographies is not discussed here. 1.2 This document outlines (1) the content of RUC and its spatial and temporal scope, (2) guidance on assessing its appropriateness for different purposes, and (3) guidance on issues arising in using RUC to examine change over time.