The regression hypothesis, first formulated by Roman Jakobson in 1941 and originally formulated on the phonology of only Slavic languages, goes back to the beginnings of psychology and psychoanalysis. It states that which was learned first will be retained last, both in 'normal' processes of forgetting and in pathological conditions such as aphasia or dementia. As a template for language attrition, the regression hypothesis has long seemed an attractive paradigm. However, regression is not in itself a theoretical or explanatory framework. Both order of acquisition and order of attrition need to be put into the larger context of linguistic theory in order to gain explanatory adequacy.