When hiring a development firm, clients have a right to expect great software that works. Some firms are unable to satisfy this expectation because their approach to software development is not focused on quality. However, a firm that incorporates test-driven development (TDD) into its development process is able to prevent most software defects from being introduced in the first place. The result: clean code that works. This white paper describes test-driven development and explains why business leaders should consider it a must-have characteristic of any development firm.