This study is an experiment research method that is pre-experimental with one group pretest-posttest design. This study aims to find out the vocabulary mastery of housekeeping students before the application of Situational Language Teaching (SLT) and describe the vocabulary mastery of housekeeping students after the application of SLT. The data in this study was collected by using tests and questionnaires. The data analysis methods used are quantitative and qualitative analysis. The theories used to answer the problems are behaviorism learning theory, vocabulary theory and situational language teaching. This research showed development of the students English vocabulary mastery after the implementation of SLT. This can be seen from how the mean scores had improved. The mean score of the pretest was 52,4. Meanwhile, the mean score of the posttest was 80.