The solubility and ferroelectric properties of (A(x)La(1-x))(2)Ti2O7 (A = Sm and Eu) solid solutions were investigated. The crystallographic structure of the solid solutions was studied using X-ray diffraction and Raman spectroscopy. The solubility limits of Eu and Sm in (A(x)La(1-x)) 2Ti2O7 were found to be greater than x = 0.5 and 0.8, respectively. The solid solutions had a monoclinic perovskite-like layered structure (PLS), similar to that of the pure La2Ti2O7, when x was less than the solubility limit. When x was above the solubility limit the materials were biphase. The biphases of (SmxLa1-x)Ti2O7 (x = 0.9) consisted of (SmxLa1-x)(2)Ti2O7 with PLS and pure Sm2Ti2O7 with pyrochlore structure, and the biphases of (EuxLa1-x)Ti2O7 (x = 0.6, 0.7, and 0.8) consisted of (EuxLa1-x)(2)Ti2O7 with PLS structure and La3+ doped Eu2Ti2O7 with pyrochlore structure. The effect of A-site substitution on the properties of La2Ti2O7 was investigated by measuring the dielectric permittivity and loss at different frequencies and temperatures. The highest piezoelectric constant d(33) was 2.8 pC/N for (Sm0.1La0.9)Ti2O7.