This paper makes a methodological contribution to the emerging field of learner corpus analysis [Granger, S., 1998. Learner English on Computer. Longman, London, 1998; Granger, S., 2002. Computer Learner corpora, Second Language Acquisition, and Foreign Language Teaching. John Benjamins, Amsterdam, 2002] and to Second Language Acquisition (SLA) research by suggesting that a corpus of learner and expert speaker correspondence, in conjunction with ethnographic data, may facilitate microgeneses of particular elements of the foreign language (FL) under study. On the basis of a 100,000-word corpus of telecollaborative correspondence, chronological pathways of "da"-compound use by learners of German are examined. Telecollaboration involves the use of global computer networks to link expert speakers and learners of particular languages for the purposes of social interaction and academic discussions over a limited period of time within an institutionalized setting. (Contains 3 tables.)