Vilfredo Pareto (1848-1923) made several important contributions 2 sociology, & in particular, econ. sociology. For instance, he introduced the concept of Pareto efficiency, which denotes an econ. allocation, whereby improvements can B made 2 at least 1 participant's well-being w/out reducing any other participant's well-being. Also, his Pareto principle is a rule of thumb that k% is taken by (100−k)% of the participants, e.g., 80% of the land in Italy was owned by 20% of the pop.