A debate that has blown hot and cold over the past several years is about to get hot again. The subject is whether the origin of hydrocarbons is organic or abiogenic, and an AAPG Hedberg Conference set next June in London, England, may go far in providing some answers. Cover photo, by Ilka von Dalwigk, shows a limestone outcrop that is part of the down-faulted Paleozoic sequence within the Siljan Ring impact structure in Sweden — an important site in the ongoing debate.<br /><em>The cover design is by Rusty Johnson.</em>