Phonological skill is widely regarded as subject to a critical period for language learning, though the nature of relevant maturational changes has yet to be clarified. Theoretical and empirical research on phonological skill development among late learners has confirmed several observable influences on short- and long-term attainment; however, these research traditions have rarely acknowledged contextual influences, much less the learner's role in the process. In this paper, I outline a number of methodological concerns for current research, and provide specific recommendations regarding participant selection, tasks, ratings and raters, factors tested, and analyses, in order to better account for influences on phonological attainment that co-vary with age.