The synthesis, reactivity, structures, and applications of the organometallic compounds of aluminum are reviewed. This article starts with a discussion of traditional synthetic approaches to aluminum alkyls, aryls, hydrides, and halides and continues with a discussion of their structures and reactivity. The following section focuses on the emerging organometallic chemistry of Al(0), Al(I), and Al(II) and specifically highlights recent developments in aluminum–aluminum bonding, insertions of small molecules and elements into Al–Al bonds, and the isolation of large metalloid clusters such as ${\mathrm{A}\mathrm{l}}_{50}{\mathrm{C}\mathrm{p}}_{12}^{*}$. Organoaluminum heterocycles and cage compounds are the subjects of the next section that briefly describes the common structural motifs and has separate subsections devoted to cage iminoalanes, alkylaluminoxanes, alkylaluminophosphinates, -phosphates, -phosphonates, and -arsonates. Structural relationships among these groups of compounds and comparisons to secondary building units in aluminophosphate molecular sieves are presented. The importance of alkylaluminoxanes to catalytic activity is also discussed. This article includes an independent section on cationic organoaluminum complexes. Although this includes more traditional cationic complexes ligated by crown ether and neutral nitrogen-donor ligands, the section emphasizes the recent developments in generating two- and three-coordinate cationic complexes. Alkide and hydride abstractions by trityl salts of weakly coordinating anions and tris(pentafluorophenyl)borane are described. Common anion decomposition pathways and successful cationic systems for oligomerizing and polymerizing alkenes are discussed. Two additional sections describe the applications of organoaluminum compounds to organic synthesis and applications in industry. Readers are referred to leading works that more adequately describe the extensive use of organoaluminum reagents in organic synthesis. Current and past applications of organoaluminum compounds for the production of long-chain alkenes and alcohols, as cocatalysts for Ziegler–Natta and metallocene-catalyzed polymerization of alkenes and dienes and catalysts for alkene oligomerization and epoxide polymerization, are summarized. Safety issues regarding the handling and disposal of pyrophoric organoaluminum reagents and waste are also discussed. One hundred thirty seven reviews and original works are cited.