In this article I make the point that there has been a continuous focus on second language development in second language acquisition research for over 40 years and that there is clear empirical evidence for generalizable developmental patterns. I will both summarize some of the core assumptions of Processability Theory (PT) as an approach to…

This chapter introduces three applications of Bayesian inference to common and novel issues in second language research. After a review of the critiques of conventional hypothesis testing, our focus centers on ways Bayesian inference can be used for dealing with missing data, for testing theory-driven substantive hypotheses without a default null…