Activity-Based Costing (ABC) is developed to improve the accuracy of product cost data derived from the traditional cost system. ABC transforms indirect (overhead) cost in the traditional cost system into direct costs by using activities as the intermediums of cost assignment. ABC traces indirect costs to the activities and then distributes the activity costs to the products. ABC has been extensively used in the practice and discussed in the literature. The purpose of this paper is to present the ABC model for joint products. A simplified illustrative case is used to demonstrate the product costing for joint products under ABC.