A simple framework is developed for representing plans, goals and resources of agents in order to model cooperative planning behavior. Plans are represented as acyclic networks of skills that, given adequate initial resources, can realize special resources (goals). Given the storage costs of resources, application costs of skills, and values of goals we can reason about the profits of a plan for an agent. We then model two forms of cooperative planning behavior between two agents, viz. fusion, aiming at the maximization of the total yield of the agents involved, and collaboration which aims at maximization of the individual yield of each agent. We present efficient polynomial algorithms for agent plan fusion and collaboration and illustrate their use with a transportation-planning example.