Résumé : The results of an experimental and theoretical study of the inertias and alignments of superdeformed bands (SD) in [Formula Presented] nuclei are presented. We show that [Formula Presented] bands tend to be distributed among three groups characterized by their alignments and the number of unpaired nucleons. The alignments cluster around integer values ([Formula Presented] relative to the reference chosen for this study), but the distribution is not strongly peaked: rather it is relatively “broad” compared with the separation, suggesting that the “strict” quantized alignments observed in some nuclei are not a systematic feature of all [Formula Presented] bands. We further show that mean-field calculations reproduce the general experimental properties and give the three band groups seen in experiment, but they do not generally reproduce the specific alignment of SD band pairs; nor, in general, do they give “good” identical bands. © 1999 The American Physical Society.