We report on an experimental study of the thermal and magnetic properties of Er75Dy25 single crystals with magnetic fields applied parallel to the [0001] and [101̅ 0] directions. The [0001] direction is the easy axis of magnetization, while the [101̅ 0] direction is the hard axis of magnetization. Three major transitions are observed in the heat capacity, magnetization, and alternating current magnetic susceptibility data. A first-order transition is observed at ∼30 K, and two second-order transitions occur at ∼45 and ∼110 K. The H-T phase diagrams constructed from the experimental data reveal that several magnetic phases, including ferromagnetic cone, ferromagnetic fan, and c axis–modulated phases, exist in an Er75Dy25 single crystal. Both similarities and dissimilarities are observed in the H-T phase diagrams of Er75Dy25 when compared to the H-T phase diagrams of pure Er single crystals.