Progress in Heterocyclic Chemistry (PHC), is an annual review series commissioned by the International Society of Heterocyclic Chemistry (ISHC). Volumes in the series contain both highlights of the previous year's literature on heterocyclic chemistry and articles on new developing topics of particular interest to heterocyclic chemists. The highlight chapters in Volume 20 are all written by leading researchers in their field and these chapters constitute a systematic survey of the important original material reported in the literature of heterocyclic chemistry in 2007. Additional articles in this volume review '2-Indolylacyl radicals in the synthesis of indole compounds' and 'Cascade reactions of carbonyl ylides for heterocyclic synthesis'.