Despite strong recent economic growth, gender inequality remains a major concern for India. This paper examines the effectiveness of a public policy geared towards the reduction of gender inequality. The national Pre-Conception and Pre-Natal Diagnostics Techniques (PNDT) Act of 1994, implemented in 1996, banned sex-selective abortions in India. Although demographers frequently mention the futility of the Act, we are among the first to evaluate the law using a treatment-effect analysis framework. Using village and town level longitudinal data from the 1991 and 2001 censuses, we find a significantly positive impact of the PNDT Act on female-to-male child sex ratio. Given the almost ubiquitous decline in the observed child sex ratio during this period, we argue that the law was successful in preventing any further worsening of the gender imbalance. We find that a possible absence of the law would have led to at least 106,000 fewer female children.