Acceptance of the claims made by researchers in any field depends in large part on the appropriateness of the methods used to gather data. In this chapter I focus on two approaches to research in second language acquisition: (a) various types of acceptability judgments or probes aimed at assessing acquisition of syntactic structure; and (b) various types of stimulated recall designed to gather learners' accounts of their own thought processes. Both methods attempt to overcome a principal problem in psycholinguistics: the desire to describe a learner's knowledge about a language based on the incomplete evidence stemming from learner production. Refinements in acceptability judgments have come from some newer multiple-choice or truth-value story tasks that allow researchers to determine the level of learner knowledge about particular syntactic structures (in the examples here, reflexives). Stimulated recall offers some additional perspectives, but its usefulness can be greatly affected by the temporal proximity of the recall to the original task; the amount of support provided to prompt the recall; and the nature and amount of training given to both interviewer and interviewee. While these newer research methods can improve the accuracy and variety of data available to SLA investigators, research methods drawn from L1 acquisition or L1 research cannot necessarily be assumed to be equally valid when used to examine L2 acquisition.