Thailand’s National Science Fair is an annual two-week event held to promote science, encourage learning and prove that science is for everyone. Derived from the first ‘Thai National Science Day’ in 1982, the fair now hosts over 1 million visitors, with exhibits from over 50 national and international companies and institutions from governmental, educational and commercial sectors. Whilst the fair is normally held in Bangkok the outreach program holds mini fairs for 32 Universities and numerous schools across the nation for local participation in science week. This paper discusses the past, present and future of the fair, incorporating existing evaluation findings and identified key challenges.