ABSTRACT
Both researchers and educators routinely call for longitudinal research on language learning and teaching. Many researchers believe that longitudinal findings can uniquely bolster our knowledge of language acquisition processes, and many practitioners find longitudinal insights particularly convincing as a basis on which to justify recommendations for educational practice. Obviously, developing advanced capacities in any language, but particularly in a second, foreign, or heritage language (hereafter, L2), is a process that inherently involves time, and a long time at that. The need for longitudinal research is particularly acute when the goals are to generate cutting-edge insights about the nature of advanced L2 capacities and to formulate sound educational practices that may enable more of our language students to attain them.
