In this paper, we study the extent and nature of informality in Colombia by using the new chapter on informality in the Encuesta Continua de Hogares (ECH) from August 2006 to December 2006, which includes new questions deepening the information on coverage of social protection benefits, labor market trajectories, and motivations for sector of employment. The availability of these new data allows us to measure informality in several ways and understand the differences and implications of using various definitions. We show that social security contributions is a reasonable measure of informality as it is a good indicator that the individual has the entire package of benefits associated with formal employment. We then use this definition of informality to characterize informal workers in various dimensions that include socio-demographic characteristics, characteristics of the firm and job satisfaction measures. * Funding from the World Bank is gratefully acknowledged; this article draws on work prepared for the Bank as part of a larger study on informality in Colombia. The findings, interpretations, and conclusions expressed in this paper are entirely those of the author and they do not necessarily represent the view of the World Bank. Any remaining errors are the author’s responsibility. Corresponding author: rbernal@uniandes.edu.co