Recent work in applied linguistics has expanded our understanding of the
rule- governed nature of language. The concept of an idealized speaker
-hearer whose linguistic competence is abstract and separate from
reality has been enriched by the notion of an actual interlocutor who
possesses communicative compe- tence, a knowledge of language which
accounts for its use in real-world con- texts. Areas of variation
previously relegated to idiosyncratic differences in performance have
been found to be dynamic yet consistent and lend themselves to study and
systematic description. Because language acquisition involves the
development of communicative competence, by its very nature it
incorporates variation and systematicity. Sec- ond-language acquisition
is similarly variable, since interlanguage is subject to the same
universal and language-specific conventions. In addition, aspects of the
second language have been found to be unevenly acquired and are differ-
entially reflected in particular contexts or settings. Yet, despite our
expanding knowledge, this variability is only beginning to be treated in
much of the sec- ond-language acquisition literature. This volume
presents the work of some researchers and methodologists who have taken
on the challenge of including variation in their research designs and
pedagogical recommendations. Variation is shown to be relevant to lin-
guistic, social, and psychological aspects of language. It is apparent
in the registers and dialects of the target language and in the inter
language of learners.