We present an argumentation-based approach to contract negotiation amongst agents. Contracts are simply viewed as abstract transactions of items between a buyer agent and a seller agent, characterised by a number of features. Agents are equipped with beliefs, goals, and preferences. Goals are classified as either structural or contractual. In order to agree on a contract, agents engage in a two-phase negotiation process: in the first phase, the buyer agent decides on (a selection of) items fulfilling its structural goals and preferences; in the second phase, the buyer agent decides on a subset of the items identified in the first phase fulfilling its contractual goals and preferences. The first phase is supported by argumentation-based decision making taking preferences into account.