Building on the existing literature, this paper constructs a simple scalar measure of inequality of opportunity and applies it to six Latin American countries. The measure--which captures between-group inequality when groups are defined exclusively on the basis of predetermined circumstances--is shown to yield a lower-bound estimate of true inequality of opportunity. Absolute and relative versions of the index are defined, and alternative parametric and non-parametric methods are employed to generate robust estimates. In the application to Latin America, we find inequality of opportunity shares ranging from one quarter to one half of total consumption inequality. An opportunity-deprivation profile that identifies the worst-off types in each society is also formally defined, and described for the same six countries. In three of them, 100 percent of the opportunity-deprived were found to be indigenous or Afro-descendants.