Rotating savings and credit associations (roscas) are informal financial organizations common in settings where communities have reduced access to formal financial institutions. In a rosca, a fixed group of participants regularly contribute small sums of money to a pool. This pool is then allocated periodically using lotteries or auction mechanisms. Roscas are empirically well-studied in the development economics literature. Due to their dynamic nature, however, roscas have proven challenging to examine theoretically. Theoretical analyses within economics have made strong assumptions about features such as the number or homogeneity of participants, the information they possess, their value for saving across time, or the number of rounds. This work presents an algorithmic study of roscas. We use techniques from the price of anarchy in auctions to characterize their welfare properties under less restrictive assumptions than previous work. Using the smoothness framework of [Syrgkanis and Tardos, 2013], we show that most common auction-based roscas have equilibrium welfare within a constant factor of the best possible. This evidence further rationalizes these organizations’ prevalence. Roscas present many further questions where algorithmic game theory may be helpful; we discuss several promising directions.