A process for ring-alkylating aniline or an aniline derivative in which aniline or an aniline derivative is reacted with an alkylating agent in the presence of an ionic liquid which includes a Lewis acid and a quaternary cation, to produce a ring-alkylated alkylaniline or a ring-alkylated aniline derivative. The use of an ionic liquid permits convenient separation of the alkylated reaction product from the reactants.