Except for a review article on radiation pressure [Am. J. Phys. (1950)], Robert T. Beyer's earliest research in nonlinear acoustics was on the increase of absorption with intensity for water and other liquids [J. Acoust. Soc. Am. (1956) (1957), and Sov. Phys.--Acoustics (1958)]. New directions soon followed: the experimental work on the parametric array [Belli et al., J. Acoust. Soc. Am. (1960) (A)], the Keck--Beyer perturbation solution for finite-amplitude waves in a viscous liquid [Phys. Fluids (1960)], and calculation of the parameter of nonlinearity B/A [J. Acoust. Soc. Am. (1960)]. Continuation and expansion of the latter work made Bob the foremost authority on B/A. Later interests include nonlinear effects in the field of a piston radiator [Ryan et al., J. Acoust. Soc. Am. (1962)], finite-amplitude propagation in a relaxing fluid, self-demodulation of a pulse [Moffett et al., J. Acoust. Soc. Am. (1970, 1971)], and various aspects of the crossed beams problem [J. Acoust. Soc. Am. (1970--1982)]. To these specific contributions must be added Beyer's book Nonlinear Acoustics and several review articles in handbooks and journals.