In today's global competitive market, the use of a manufacturing system that seeks waste elimination and creating more customer value such as the lean manufacturing system becomes crucial. At the same time, companies seeking lean implementation should better think of lean as a management philosophy and not as a set of tools. Consequently, managers should continuously search for ways to surpass any obstacle hindering their motivation to implement the lean philosophy. Simultaneously, management accountants should also develop ways to tailor their current management accounting tools to meet their lean needs. This book proposes a framework that suggests the implementation of activity-based costing to cost products in lean firms in conditions where some shared resources are still available. This is in attempt to draw management accountants' attention to the idea that having a condition of shared resources shall not lead them to back off from implementing a lean manufacturing system nor shall it lead them to compute distorted product unit costs. However, the use of activity-based costing may even yield various positive implications that enhances the competitive stand of their companies.