This chapter analyzes significant background characteristics found among Mexico's legal opposition leadership, examines national electoral trends among opposition parties since 1982, and suggests that differences between mass support for and leadership of opposition groups. It explains about the possible impact differing leadership characteristics may have on Mexico's future political stability. Since 1968, Mexico's political system has undergone a severe crisis of legitimacy. During the last two decades Mexico's leadership, whose direct antecedents dominated the political scene since the 1920s, tinkered with the electoral process as a way of encouraging political opposition and legitimizing their own rule. With political technocrats, who have few mass brokerage skills, dominating establishment leadership, deputies who have grass-roots contacts and experiences, whether they are from the opposition or the official party, will be in greater demand. Discrepancies between leadership backgrounds and sources of support are likely to have important future consequences for Mexico.