We initiate a study of tradeoffs between communication and computation in well-known communication models and in other related models. The fundamental question we investigate is the following: Is there a computational task that exhibits a strong tradeoff behavior between the amount of communication and the amount of time needed for local computation? Under various standard assumptions, we exhibit Boolean functions that show strong tradeoffs between communication and time complexity in the following scenarios: Two-party communication complexity. We exhibit a polynomialtime computable Boolean function that has a low randomized communication complexity, while any communicationefficient (randomized) protocol for this function requires a superpolynomial amount of local computation. In the case of deterministic two-party protocols, we show a similar result relative to a random oracle. Query complexity. We exhibit a polynomial-time computable Boolean function that can be computed by queryi...