This study uses three key South African national household survey instruments the 1993 Project Statistics for Statistics of Living Standards and Development, the 1995, 1997 and 1999 October Household Surveys, and the September 2000 Labour Force Survey to identify the problems involved in capturing information on who works in the informal sector and the kind of work they do. These problems are discussed in reference to the difficulties that arise in determining whether or not people are working and in capturing this work as either formal or informal sector employment. The surveys are also examined to determine how survey design has contributed to improving the capture of informal sector work. The resulting data sets are used to chart the expansion in the estimated size of the informal sector. One of the implications of continually improving measures of informal sector employment, however, is that it is difficult to evaluate how much of the recorded expansion in this employment reflects a real increase, and how much derives from the improved capture of this work.