This paper presents the performance of retention-type earthen dams subjected to steady-state seepage and pseudostatic loading conditions. For this, an earthen dam section having a height of 7.2 m, side slopes of 1H:1V, and a horizontal drain with varying geometry for seepage control is considered. The normalized length (Ld/H) and thickness (td/H) of the horizontal drain (HD) as measured from the toe towards the downstream side varies from Ld/H = 0 (i.e., fully clogged drain) to Ld/H = 1.31 (i.e., up to mid-length of the crest), and td/H = 0 (i.e., fully clogged drain) to td/H = 0.140. The results are presented in terms of variation of phreatic surface, pore-water pressure at a distance of 0.25H from the downstream toe, seepage flux below the crest, and factor of safety (both static and pseudostatic) of the downstream side slope. The earthen dam (having 1H:1V side slopes) filled with maximum upstream water level (hF/H = 0.9) and a fully clogged drain witnessed a factor of safety (FS) less than unity at the downstream side during the static condition (KH = 0) itself. Earthen dams with a fully functional horizontal drain are stable (FS > 1) during steady-state seepage conditions. However, when subjected to inertial (or pseudostatic) loading in the form of horizontal seismic coefficient (KH), the FS values decreased. Further, parametric studies were conducted to understand the influence of side slope inclination on the seepage-stability behavior of retention dams. Furthermore, numerical analyses of retention-type earthen dams were compared and validated with centrifuge tests conducted on earthen dam models (with and without HD) having identical geometrical and material characteristics. The analyses and interpretation of centrifuge test results for retention-type earthen dams subjected to flooding and psuedostatic loading are presented and corroborate well with numerical analysis results.