Modern theories of second language acquisition (SLA) have put emphasis on the learner's active creative role and on natural linguistic constraints which govern the acquisitional process. The two notions of learner creativity and natural constraints are generally, in one form or another, considered to be essential aspects of the process of SLA. Yet it is not always clear how they are thought to interrelate. Obviously, there is an inherent dualism in viewing the learner on the one hand, as an active operator, and on the other, as subject to constraints which make him follow preconditioned paths. In SLA research, one of these aspects will often seem more central to the purpose of study than the other, and will therefore be focused more. Thus, in some areas of L2 research, typically studies in a communicational and interactional perspective, the learner's purposefulness has generally been foregrounded, and options, strategies, and choices have been matters of central interest. In other areas, typically studies dealing with developmental patterns and acquisitional routes, the focus has rather been on the ‘constraint’ aspect, and the concern has been more with uniformity, predictability, and conditioning factors. The hypothesis of a ‘natural route of interlanguage development’ has become a central notion here. The linguistically inherent constraints on the shaping of the learner language have been analyzed in terms of notions such as markedness relations, simplification, and transfer.

The standpoint taken here is that we are dealing with the same general process of SLA in all the cases mentioned, and that it is important to join together the two perspectives of ‘strategic creativity’ and ‘natural constraint’ into an integrated view.