From the last two decades of the 20th Century on, many companies have adopted production strategies that could be termed “lean manufacturing”. Lean team leaders state that traditional costing systems fail to properly assess their operational improvements and therefore ask for new cost accounting methods. The search for a new accounting paradigm has led to important applied research and several accounting methods. In this paper we are going to show the state of the art in costing techniques used in companies that adopt lean manufacturing practices and we will be presenting an additional costing method, based on Activity-Based Costing, intended to cast light on the operational improvements achieved in companies that are just starting a maturity path towards lean manufacturing. This article examines how the approach is applied in the context of a manufacturing company.