This study traces the individual learning trajectories of an adult beginner L2 Finnish learner in expressing the extralinguistic concept of evaluation from a dynamic usage-based perspective. Our results provide support for the view of learner language as a dynamic system in which patterns wax and wane and in which a change in one component has the potential to affect the whole system. In the early stages of learning there was a strong preference to use lexical verbs first, and then adjectives. The study also shows that variability plays a role. Finally, the study confirms that the learning of L2 constructions is in some cases item based. However, another highly frequent and superficially similar verbal construction in our data did not develop from a fixed formula. The role of instruction and the learner’s explicit knowledge as well as possibly input frequencies may have played a role in the different developmental trajectories.