The “ MORPHS ” group has obtained an extensive spectroscopic dataset of galaxies in the fields of 10 rich clusters at 0.37 < z < 0.56 ; the stellar population properties of about 700 objects have been determined from a detailed analysis of spectral line strenghts and colours , up to a galactic absolute magnitude M _ { V } = -20.3 mag .
Morphological informations for a consistent fraction of our sample have been previously derived from deep images of the central regions of these clusters taken with the WFPC-2 on board the HST .
Spectral and morphological features can be compared in order to study the star formation histories of the different galactic types in clusters ; here we show some preliminary results of this comparison .