Lanthanide ion doping of lead titanate was investigated using structural and differential scanning calorimetry measurements. Dense ceramics samples were prepared with starting compositions, Pb1−3x/2Ln x TiO3, assuming A-site substitution of Ln = La, Nd, Sm, Eu, Gd and Dy, at 2 and 8 at.%. Doping with La3+ reduced the tetragonality and cell volume. A systematic recovery in these values was observed for the smaller Ln3+ ions, suggesting the onset of partial substitution of the Ln ions at the B-site. The ferroelectric–paraelectric transition temperatures also recovered, consistent with an increased probability of B-site occupation with decreasing ion size. Evidence for site occupancy obtained from the presence cation vacancies is also discussed.