-ct'he aim of this study was to investigate the effects of motivation ( intrinsic and extrinsic ones ) and vocabulary knowledge on reading comprehension. A total of 108 randomly selected grade 12 EFL students ( Females=47; Males=61) of Ghion Secondary and Preparatory School participated in the study. Motivational questionnaire and tests of vocabulary and reading comprehension were used to gather data. Pearson product moment correlation and multiple regression analysis were used in data analysis. The results of correlation analysis indicated that all the independent variables significantly related to each other and with reading comprehension. Results obtained through regression analysis also revealed that EFL students' vocabulary knowledge was the independent variable that .... strongly predicted reading comprehension. Similarly, intrinsic motivation was found to be independent predictor of reading comprehension. But extrinsic motivation was found to be not independent predictor of reading comprehension in this study. The combined effect of all the independent variables was so strong (i.e. ,69.1%)