This paper will report how practicing teachers implement an interdisciplinary curriculum in Hong Kong classrooms. General Studies, as an interdisciplinary subject first developed for primary curriculum, has essential contribution to enhance meaningful learning relevant to daily experiences and develop pupils' high order thinking skills. Thus, the realization of the intended aims and objectives of this curriculum is of pivotal importance for the achievement of the overall aims of education for the 21st century. Through questionnaire survey, pre and post-lesson interviews and lesson observation, the researchers examine whether intended aims of the General Studis Curriculum have been achieved. Implications and suggestions will be discussed in relation to professional development of practicing teachers on integrated teaching.