Tetrahydrocarbazoles have been prepared in one‐flask syntheses from indoles, ketones or aldehydes, and maleimides, with acid catalysis. The reactions involve a condensation of the indole with the ketone or aldehyde, followed by an in situ trapping of the vinylindole in a Diels‐Alder addition with a maleimide. Isomerization of the double bond into the indole nucleus gave the tetrahydrocarbazoles which were isolated (6, 9, and 10). Variation of the indole, carbonyl compound, and maleimide has been explored. The predominant stereochemistry of the tetrahydro ring in the products is all‐cis, although a second stereoisomer has been isolated. Two regioisomers were generated from all unsymmetrical 2‐alkanones, except 2‐butanone, which gave the single isomer 9a. Aromatization of tetrahydrocarbazoles 6 to carbazoles 7 was accomplished with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone.