Mexico's socioeconomic model prior to 1980 is commonly referred to as Import Substitution. The process of change in Mexico's industrial relations system can be divided into three periods: first, 1984-1992, when efforts to make collective contracts more flexible began; second, 1992-1994, when there was an attempt to restructure union corporatism; and third, the period of economic and political crisis around neo-liberalism, which began in 1994. 1982 was a major turning point for Mexico s socioeconomic system and for changes in its industrial relations system, although the latter has been marked by waverings and shifts. Conceptions regarding labour flexibility as employer strategies supported by the state became more widespread in Mexico from 1984 to 1992. The chapter summarizes the degree to which and the ways in which flexibility has been increased in collective contracts and the corporate policies across different economic sectors since 1984.