This paper examines the optimal bundling strategies of a multiproduct monopoly in markets in which a seller cannot monitor and thereby restrict the purchases of buyers to a single bundle, while buyers have resale opportunities. In such markets, the standard mechanism through which bundling increases seller profits, based on price discrimination, is not feasible. The profit-maximizing bundling strategy is characterized, given the restrictions on pricing policies resulting from resale and a lack of monitoring. The welfare implications of optimal bundling are analyzed.