This study evaluates the effectiveness of Test-Driven Development (TDD) in software projects through a multi-case analysis of two distinct projects, one employing TDD and the other using a traditional approach. Results indicate that TDD enhances code quality and team productivity significantly compared to non-TDD approaches, evidenced by lower defect rates, higher customer satisfaction, and improved design quality metrics. The findings suggest that TDD leads to more modular and less complex code structures, ultimately benefiting the software development process.