We match administrative panel data on contributions to the Chilean mandatory defined contribution pension system with large scale survey data including measures of financial literacy and pension knowledge. We use this data to analyse the individual’s decision to opt out of the low-risk, low-return default investment portfolio, their decisions to contribute to the system, reactions to changes in administrative fees, and their returns of the portfolio choices. To address the endogeneity of financial literacy and pension knowledge to contribution behaviour and savings decisions, we use collect information from a recent pension reform and make use of this in an instrumental variable approach.