Abstract:In codeswitching contexts, the language of a syntactic head determines the distribution of its complements. Mahootian 1993 derives this generalization by representing heads as the anchors of elementary trees in a lexicalized TAG. However, not all codeswitching sequences are amenable to a head-complement analysis. For instance, adnominal adjectives can occupy positions not available to them in their own language, and the TAG derivation of such sequences must use unanchored auxiliary trees. palabras heavy-duty `heavy-duty words' (Spanish-English; Poplack 1980:584) taste lousy sana `very lousy taste' (English-Swahili; Myers-Scotton 1993:29, (10)) Given the null hypothesis that codeswitching and monolingual sequences are derived in an identical manner, sequences like those above provide evidence that pure lexicalized TAGs are inadequate for the description of natural language.