This research is aimed to get the empirical data whether or not there is any significant relationship between the eleventh grade students? reading and vocabulary mastery. It was held in SMAN 57 Kedoya. It was conducted in the 3rd and 4th week of January 2007. The variables of this research are reading as independent variable and vocabulary as dependent variable. The writer took data by using test instrument. The instruments of this research are reading test and vocabulary test. To find the relationship between students? reading (variable X) and vocabulary mastery (variable Y) the data were analyzed by using Person?s Product Moment Correlation since the data of both variables normally distributed. The result of this study shows that the r-observed is 0.89 and r-table is 0.349. Since the r-observed is higher than r-table (0.89 > 0.349), the research hypothesis (Hi) is accepted and null hypothesis (Ho) is rejected. It was also found that the amount of the contribution of the variable X to the variable Y is 79.21%. Therefore, it is concluded that there is a significant relationship between the eleventh grade students? reading and vocabulary mastery.