Interlanguage studies have found learners' use of internal modifiers to develop in terms of frequency, choice and variety over time spent in the target speech community. Much of this research has, however, concentrated on syntactic and lexical downgrading. Studies focusing on upgrading, i.e., intensifying forms of internal modification, remain in very short supply. This study focuses on the acquisition of upgrading in refusals of offers by 33 Irish learners of German over a period of 10 months spent in a study abroad context. Learner, German NS, and Irish English NS data were elicited using the free discourse completion task specifically designed to investigate discourse sequences. Contrary to previous findings, learners were found to employ upgraders to an extensive degree in refusal sequences prior to the year abroad. However, their use of upgraders in initial refusals was low prior to their sojourn abroad. Over time, upgrading in initial refusals increased in an L2-like movement. This development is explained by a decrease in negative transfer from Irish English in the structuring of offer-refusal exchanges, a change which led to a decrease in ritual reoffers and a consequent increase in the use of upgraders to intensify the force of the initial refusals or of the adjuncts employed therewith. In addition, the linguistic evidence points to a higher level of upgrading in initial refusals realized using formulaic utterances relative to those realized using ad hoc utterances at the end of the year abroad, a finding which underlines the explanatory power of the complexification hypothesis in explaining the acquisition of modification by learners.