Absorption emission and excitation spectra are measured and analyzed to achieve assignments of energy levels for 4f(N) ions in Ba2YCl7:RE3+ (RE = Pr, Nd, Tb, Dy, Ho, Er, and Tm) crystals. The experimental energy levels were analyzed in terms of the usual free-ion parameters and the crystal field (CF) ones, B-kq, in the Wybourne notation. The orthorhombic C-2v symmetry is shown to be a good approximation of the actual triclinic C-1 site symmetry at the metal center. The starting values of the CF parameters B-kq used for fittings for the studied crystals were obtained from superposition model analysis. A good agreement between the calculated and experimental energy levels was obtained with rms deviations in the range from 6.8 cm(-1) (for Ho3+) to 14.1 cm(-1) (for Pr3+). The fitted sets of B-kq parameters are, in general, consistent across the 4f(N) series. This study has enabled, determination and discussion of the trends in variation of the free-ion parameters and CF ones across the 4f(N) series. The CF parameter set and energy level structure obtained for Nd3+ ion in Ba2YCl7 crystal are consistent with those for Nd3+ in structurally related RbY2Cl7 crystal. This systematic analysis of CF parameters is one of only few such studies encompassing nearly whole series of RE3+ ions.