Mabel Alter took her ballettraining with Lilly Green and Sonia Gaskells Ballet Recitel. She was a dancer with the Ballet van de Nederlands Opera, het Nederlands Ballet and the Nederlands Danstheater.
Several of her favourite choreographers, she danced their repertoire - are: Rudi van Dantzig, Hans van Manen and George Balanchine. She founded her own balletschool in The Hague in 1970 'Balletschool Mabel Alter'. Besides her own balletschool she enjoyed teaching at the Rotterdamse Dansacademie. At present she is teaching basic balletclass for young adults in the balletschool which is now in owned by her daughter Mirella Simoncini. Her teaching skill is strong on placement of the body and how to discover and show the feeling of a dancer!