Cement-based materials modified with latexes are well known for their excellent durability properties and are therefore widely used in demanding repair and restoration environments. The addition of polymers significantly affects the mechanical behavior of mortars and concretes, particularly their viscoelastic properties. This study presents the dynamic-mechanical analysis (DMA), which is an established analytical technique in polymer science, as a method to obtain dedicated information on the contribution of styrene acrylate and styrene butadiene latexes to the viscoelastic properties of hardened cement pastes. At sample ages of 28 days, cement pastes modified with varying polymer dosages were tested by means of DMA. A particular focus was put on interpreting the obtained results with regard to the microstructural characteristics investigated using scanning electron microscopy and porosimetry. The results reveal that the glass transition temperature of the latex is the dominant factor affecting the viscous properties of the pastes, while the pores that are formed due latex additives have a larger impact on the elastic paste behavior. Additionally, determining the frequency-temperature-dependent behavior using dynamic-mechanical analysis presents a promising pathway to more efficient testing techniques regarding the long-term mechanical behavior of cementitious materials.