We examine the impact of Freeman and Medoff's seminal book What Do Unions Do? on the field of Industrial and Labor Relations, in the 25 years since its publication. While it is widely accepted that this book has had a major impact on its field, we attempt to quantify this by using various bibliometric indicators (e.g., h-index) and descriptive statistics; via a combination of manual literature review and specialized citation software using multiple databases. As expected, our findings quantifiably indicate that What Do Unions Do? has had and continues to have an above average impact on in its field.