This study seeks to: (1) assess students’ vocabulary mastery levels before and after utilizing the Secret Door approach; and (2) ascertain whether employ- ing the Secret Door method enhances students’ vocabulary. This supports the idea that using the Secret Door approach improves pupils’ vocabularies. Pre- experimentalOneGroupPretest-PosttestDesignwithaSampleof16Students from Class X IPS 2 and Cluster Random Sampling Technique is the design employed in this study. The test served as an instrument for the researcher to gather the data. Data research revealed that applying the Secret Door approach increased students’ vocabulary mastery. It can be proven by the t- testvalueof-27.547whichislessthanthet-tablevalueof2.602,whichmeans thatH0ofthisresearchwasrejectedandH1wasaccepted.Therefore,itcanbe concludedthattheuseoftheSecretDoormethodimprovestudents’vocabulary at the first year students of Vocational Secondary School in SouthSulawesi.