McIntosh and Munk claim that the class schema developed by Erikson and Goldthorpe lacks validity and should not be taken as a basis for studies of intergenerational social mobility. Their paper is founded on a serious misconception of why the schema is in fact used by sociologists in mobility research and, for this reason, their test of its validity is essentially misdirected. In addition, the test itself is not carried out in an appropriate way nor, it would seem, with data of adequate quality.