This paper represents an inquiry into employment inequality between population sub-groups. The first, and most obvious, starting point to this inquiry - and which forms the subject matter of this paper - was to ask how such inequality should be measured. This question was answered in terms of an idea adapted from the area of income inequality. This was to use, as the inequality index, the natural logarithm of the ratio of the arithmetic mean, to the geometric mean, of the employment rate, where the latter was defined as either the proportion of the working-age population, or the proportion of the labour force, that was employed. It was shown that such an index had several attractive properties and also admitted of an appealing interpretation in terms of social welfare.