Activity-based costing (ABC) is a costing methodology that assigns costs according to actual consumption by assigning costs of activities to products and services. It has become more important for manufacturing firms as indirect costs have increased relative to direct costs with advances in technology and automation. The document examines how internal factors like support systems, resources, management support, and accountant competency affect ABC implementation and firm performance, with a focus on accurate product costing, inventory valuation, and financial reporting. A survey will be used to study the impact of ABC implementation on decision making, cost planning, financial reporting, and competency at manufacturing firms in Pakistan.