More than a hundred physicists with various interests in the plasma heating problem, mainly from Europe and the USA, attended this Course of the "International School of Plasma Physics" in the Villa Monastero at Varenna, in the most splendid scenery of Lake Como. The Symposium – a combination of School and Conference directed by W. Hooke (Princeton University) – was organized by the Plasma Physics Laboratory of the CNR – Milano (directed by Professor P. Caldirola) and sponsored by the Italian CNR and CNEN and by EURATOM. As many as sixty lectures and seminars were held during eighteen plenary sessions on r. f. -heating, turbulent heating (TH), Ohmic heating, compressional heating, neutral-beam injection (NBI), relativistic electron beams (REB) and laser interaction.