Small amounts of hydrogen-bonding comonomers such as N-(2-methacryloxyethyl)ethylene urea (MEEU) are often included in latex particle synthesis to promote adhesion of latex films to metals and old surfaces. Little is known about how these monomers affect the latex film formation process. Here we examine the influence of 1-7 wt.% MEEU on butyl acrylate-methyl methacrylate copolymer latex films using fluorescence resonance energy transfer (FRET) measurements, in conjunction with donor- and acceptor-labeled latex particles, to study the rates of polymer diffusion in these films. The presence of MEEU in the copolymer leads to small increases in the polymer glass transition temperature (Tg). It also tends to retard the rate of polymer diffusion. This effect, however, is very sensitive to the humidity of the surrounding atmosphere. It appears that moisture taken up in the film minimizes the influence of MEEU groups on the rate of polymer diffusion. (C) 2010 Elsevier Ltd. All rights reserved.