What is the trend of unconventional participation in Italy and how do we measure it? This article analyzes the rise of unconventional participation in Italy from 1976 to 2009, focusing on measurement equivalence over time to produce unbiased estimates and to meaningfully compare means. The results show that the concept and the measure of unconventional participation are unidimensional and equivalent across time. Further, there has been a significative increase in the levels of unconventional participation and a differentiation in its distribution.