This tutorial review presents some recent examples of intramolecular Diels-Alder (IMDA) reactions as key complexity-generating steps in the total synthesis of structurally intricate natural products. The opportunities afforded by transannular (TADA) versions of the IMDA reaction in complex molecule assembly are also highlighted. The review is aimed at a wide audience, ranging from advanced undergraduates to seasoned practitioners of total synthesis; since this is an educational overview, only selected highlights from the period 2000-2009 are presented, along with chosen references to other, more comprehensive, reviews.