ABSTRACT
The ambitious nature of the studies and of the volume as a whole, trying to charter a very vast territory while at the same time maintaining a coherent outlook, raises important theoretical and methodological questions for SLA research. The first is the extent to which it is possible to provide unitary empirical accounts of wide-spanning relationships or whether investigations should necessarily be limited to more local questions and domains. This implies discussing the identity of the SLA and multilingualism research fields, the opportunities for integration, and the risks of disintegration. The second is the issue of prediction and generalization, which have been repeatedly called into question in recent theoretical debates. It is argued that the complexity of the research object and questions should not lead to pessimistic or nihilistic conclusions, limiting the domain of what can legitimately be said to the description of individual cases, but should, on the contrary, promote more generalizable interdisciplinary research. This, in turn, requires cooperative, constructive attitudes, appreciating similarities between approaches and opportunities for collaboration rather than overemphasizing differences and engaging in sterile academic confrontations.
