This study investigated reading strategies used by a sample of eight successful senior high school readers who were asked to express the meanings of selected unknown English vocabulary from the textbook. The data was collected by means of the think-aloud procedure: Participants were asked to verbalize the manner in which they deduced the meanings of unknown English vocabulary. Analysis revealed that a total of six kinds reading strategies were identified in this study: Using context clues, looking up words in the dictionary, inferring, activating prior knowledge, comparing and contrasting the text, and paraphrasing. The strategies of ”using context clues” and ”looking up words in the dictionary” were the most commonly used strategies when reading unknown English vocabulary among these successful readers.