Concepts such as dependability/generalization and inferences are dealt with implicitly or explicitly in any research undertaken in applied linguistics. This volume provides a well-balanced and cross-disciplinary perspective on how researchers conceptualize inferences about learner acquisition and performances as well as dependability and generalizability of findings. The book is a collection of chapters by prominent researchers in applied linguistics, working in diverse domains such as vocabulary, syntax, discourse analysis, SLA, and language testing. The goal of the book is to bring attention to these issues, which underpin much of applied linguistics research and to highlight what is considered good practice so as to buttress confidence in the research claims made. The book represents current thinking on fundamental research concepts in applied linguistics and can be used as a textbook in courses on research methodology in applied linguistics. The book is also an excellent source of in-depth analysis of research conceptualization for applied linguistics researchers and graduate students.