The degree and type of optionality that characterizes L2 grammars has been at the core
of the L1/L2 divide since at least the late 1970s. Some early characterizations of L2 syntactic
optionality inspired performance failure accounts (Adjémian, 1976; Epstein et al.,
1996), but representational accounts, and specifically parametric variation were already
subsumed in Liceras’ (1983, 1986) notion of ‘permeability’ and in Pérez-Leroux and