The 2004 Brouwer Award was given to the quiet and generous John Papaloizou (Cambridge University), for his major contributions in areas such as the radial-orbit instability in anisotropic stellar systems, toroidal modes in rotating stars, thermal instability in accretion disks, and the collapse and fragmentation of gas clouds. His two seminal contributions have been to the stability of accretion tori (he remains famous for the Papaloizou-Pringle instability) and the evolution of protoplanetary disks. His recent work has included topics such as criteria for gap formation by massive planets and the effects that interactions with the disks have on the evolution of a planet's semimajor axis and orbital eccentricity. Papaloizou's invited lecture at the 2005 meeting was entitled "Instabilities and Transport in Differentially Rotating Rings and Disks".