In recent years research on comparative typology has led to reveal regularities and to formulate new constraints upon variation for a broad range of phenomena. As the amount of typological research increased, a growing interest arose for the implications that findings in the typological field might have on second language acquisition. Written by experts in the field of typology and/or second language acquisition, this volume addresses theoretical and empirical issues on structural domains such as relative clauses and possessive constructions as well as pragmatic considerations on information organization in learners productions.