The Zeeman splittings of the lowest J = fraction five-twos, J = fraction seven-twos multiplet levels for Ce³⁺ in LaCl₃ have been investigated using pulsed magnetic fields up to 200 KG. The results are compared with static crystal field theory and it is suggested that, whilst the overall agreement is good, the discrepancies may indicate a significant contribution from phonon interaction. Crystal field parameters and wave functions are also reported for Ce³⁺ in LaBr₃. These have been obtained from measurements in zero magnetic field.