This paper presents a Work Breakdown Structure (WBS) for a phased implementation of an Enterprise Resource Planning (ERP) solution. The key activities that constitute an ERP implementation project are discerned in detail, each in its entirety. Each activity illustrates the tasks required to fulfill each part of a project. The potential challenges that are usually encountered in every selected activity are discussed. Finally, using a WBS to cost an ERP project is proposed. ERP has been referred to as a business operating system that enables better resource planning and improved delivery of value-added products and services to customer.