The serviceability design of wood-frame residential floors in Canada has departed from use of the traditional deflection criterion based on maximum deflection under uniform loading. Laboratory and field research in the 1970s and 1980s, led, in 1990, to the adoption of a new criterion in the National Building Code of Canada. This criterion is based, in part, on limiting the deflection of a floor system under the action of a concentrated load of 1 kN. Aspects of floor performance that a serviceability criterion is designed to limit and the progress made to extend these requirements to other than sawn lumber joist floors are reviewed. Current and future research needs are outlined.