The 12th International Conference on Plant Growth Substances was held from 26th to 31st August 1985 in Heidelberg, F. R. G., under the auspices of the IPGSA (International Plant Growth Sub stances Association) and the University of Heidelberg in its 599th year. As many as 750 participants from 40 countries all over the world attended the conference, including guests and staff members of the local organizers. Fine days provided an excellent background for a fruitful and pleasant meeting and all the activities accompanying the scientific programme. During the conference all current aspects concerning growth substances were treated. Altogether the par ticipants presented 207 oral reports organized in four parallel sessions and about 300 posters, for which 2 hours' poster sessions were reserved each day. The conference gained in perspective from the arrangement of five workshops in which special aspects and the most recent results could be presented by specialists in the particular fields. The topics of the workshop were: actual methods of hormone detection (orga nizer H. Kende), auxin transport (organizer R. Hertel), growth sub stances and tumour formation (organizer J. Schroder), evolution of the hormone system (organizer W. Jacobs) and problems of ap plication (organizer J. Jung). The abstracts of all presentations were collected in a Book of Abstracts available during the conference, giving a rough surveY of the whole field of plant growth substances in its present state."