Polymer-modified hydraulic cement mixtures (PMC) are widely used for a variety of applications. The literature to-date on PMC is considerable but little has been published examining the effect of variables within the polymer on the properties of PMC. The work described in this paper attempts to partially fill this void. The studied variables include polymercement ratio, latex particle size, glass transition temperatures, effect of carboxylation and pH value. Also the effect of wet and dry curing of PMC is examined. The theory of polymer-modification of hydraulic cement mixtures is discussed in light of these results.