The complexities inherent to the acquisition of temporal reference have not been associated with the first formal means of representing time in L2 acquisition of temporal reference, namely temporal adverbials. But this study of the use of ‘then’/‘after that’ by Vietnamese and Chinese learners of ESL suggests that this temporal adverb poses as much of a learning challenge as morphological means of temporal reference. A distinct form to function mapping is evident in this learner's use of ‘then’/‘after that’, just as it is in interlanguage morphological marking of tense and aspect. The same asymmetry in the learning process is evident, with target-like form being acquired at a point at which the corresponding function is still not completely target-like. ‘Then’/‘after that’ marks chronological order for salient narrative events. This paper shows that this learner's usage is monitored by a looser notion of salience, which emerges from the transference of a salience-marking principle from a tense-free L1. It is suggested that since the tenseless L1 is clearly impacting not just the acquisition of English tense-aspect morphology, but rather the entire system of temporal reference, the teacher should not assume shared intuitions on the felicitous use of ‘so simple a word’ as then. Felicitous target usage of ‘then’/‘after that’ should be introduced as a subset of what the learner assumes to be acceptable. In this, negative evidence can be used to illustrate the more highly constrained nature of target usage.