Solid-liquid equilibria for three isomeric binary mixtures of 3-aminophenol (1) + 2-aminophenol (2) (eutectic temperature T-E = 376.5 K, eutectic composition x(1E) = 0.86), 4-(acetylamino)toluene (1) + 2-(acetylamino)toluene (2) (TE = 357.2 K, X-1E = 0.30), and 3,4,5-trimethoxybenzoic acid (1) + 2,4,5-trimethoxybenzoic acid (2) (TE = 395.8 K, X-1E = 0.33) were measured using differential scanning calorimetry (DSC). Simple eutectic behaviors for these systems were observed. The experimental results were correlated using the Wilson activity coefficient model. The eutectic compositions were also determined using Gray's model and the fractional transformation method.