In this article, labour informality in Chile is examined through an analysis of its measurement, trends and driving factors. The article contains a review of the theories and methods used to measure informality, as well as a quantitative analysis that draws on data from the National Employment Survey of the National Institute of Statistics of Chile. The study comprises a descriptive overview of trends in informality and an inferential analysis using logit and probit regression models. The findings show that the probability of being in informal employment is higher for women and for those who have a lower level of education and are engaged in small businesses and in low-productivity sectors. These trends have been consistent over time, underscoring the need for policies that take into account both individual characteristics and those of the productive environment in order to address labour informality in Chile.