The decay pathways of the lowest singlet and triplet excited states (¹trans* and ³trans*) of trans-n-styrylanthracenes (n-StA, where n= 1, 2 or 9 on the anthracene) have been studied in acetonitrile at room temperature. Fluorescence lifetimes (τ_F) and quantum yields (ϕ_F), as well as the yield and spectral and kinetic properties of the lowest triplet state of the three StAs, were determined by steady-state and transient techniques. The formation and the decay of the respective StA radical cations (trans^˙+) were observed by laser flash photolysis; the yield of photoionization is ca. 0.07 on 353 nm excitation and is enhanced by fluorescence quenching with 1,4-dicyanobenzene. The formation and decay of the StA radical anions (trans^˙–) in the presence of diethylaniline (DEA) is concluded from transient conductivity (Δκ) and optical results. DEA significantly enhances the yield of trans^˙– and the initial amplitude of Δκ and correspondingly quenches ϕ_F. The bimolecular interaction between ¹trans* and 4-bromodimethylaniline enhances the triplet population.