Abstract of thesis entitled How does joining Government Procurement Agreement affect bilateral services trade ? ------A Case Study of the United States Based on the Gravity Model. Submitted by Zhang Lixin (M-B1-5604-9) for the degree of Master of Social Sciences in Economics at the University of Macau in May 2013. Government procurement has been playing a more important role in international services trade than before since government services and government construction services were included in the Government Procurement Agreement (GPA) in 1996. But so far, few studies put focus on the effect of GPA on bilateral trade flows. There is no empirical work for GPA in existing literature, most of which does qualitative analysis instead of quantitative analysis. This thesis attempts to fill the gap in literature by employing the gravity model to examine how joining GPA affects bilateral service trade flows between the United States and its primary 26 trade partner countries by using panel data from 1992 to 2005. In the gravity model, some other factors are also taken into consideration. The empirical results indicate that joining GPA has significant positive effects on bilateral services trade flows, and the effects grow stronger year by year. Some other factors, such as GDP, a common language and a common border, are also significant. Based on the empirical results of the United States' experience, some general policy implications and suggestions are given about joining GPA and how to promote services trade.