The main claim of the present article is that the preparatory session of the author's academic training program for English enables the participating students to develop a larger vocabulary of the language when it is said that university students generally fail to improve their English proficiency including vocabulary after matriculation. This program consists of a nine-month preparatory session at Kyushu University starting in November and a three-week overseas session held at Pembroke College, the University of Cambridge, in August and September of the next year. The participants are required to devise a plan to study English and the British culture for the long preparatory session. They have four vocabulary quizzes during the preliminary part of the program and their scores show gradual improvement, which means that the training program constitutes a considerable contribution to the development of a stronger personal vocabulary. The advantageous feature of the training program related with vocabulary points to the preferable existence of the preparatory period and thereby the usefulness of the program as a whole.