The objectives of this research are to find out the correlation between (1) the students’ vocabulary mastery and students’ English achievement; (2) the students’ reading comprehension and students’ English achievement; and (3) the students’ vocabulary mastery and reading comprehension toward students’ English achievement. The study is conducted in October to November 2015 at SMP Negeri 5 Sragen. The population is all of its eight grade students, while the sample group is 32 students of VIII C which is taken by cluster random sampling technique. The researcher uses descriptive research method, with category of correlational study. The instruments in collecting the data are test and document from the English teacher. The techniques which are used to analyze the data are Simple Correlation and Multiple Regression Correlation. The result of the data analysis shows that in the level of significance α = 0.05 (1) there is a positive correlation between the students’ vocabulary mastery and students’ English achievement(rx1y= 0.373 and to = 2.13>tt = 1.7), and it is about 13.92%; (2) there is a positive correlation between the students’ reading comprehension and students’ English achievement(rx2y= 0.465dan to = 2.78>tt = 1.7, and it is about 4.,51%; and there is a positive correlation between the students’ vocabulary mastery and reading comprehension toward students’ English achievement(Ry12 = 0.4683danFo = 3.80> Ft = 3.35), and it is about 21.93%.
Based on the result of the study, it is known that the first hypothesis saying that there is a positive correlation between vocabulary mastery and students’ English achievement is accepted. The second hypothesis saying that there is a positive correlation between reading comprehension and students’ English achievement is also accepted. Meanwhile, the third hypothesis saying that there is a positive correlation on vocabulary mastery, reading comprehension simultaneously and students’ English achievement of the eighth grade students of SMP Negeri 5 Sragen in the academic year of 2015/2016 is also accepted.
The result of the research shows that vocabulary mastery and reading comprehension are important variables and effective factors in the effort of improving students’ English achievement. Therefore, vocabulary mastery and reading comprehension should be considered in increasing students’ English achievement, although the factors are not only come from those variables.
Key words: Vocabulary Mastery, Reading Comprehension, and Students’ English Achievement