第二语言习得（SLA）是对学习，使用，有时失去母语以外的任何形式的语言的系统研究。SLA是一个新兴的研究领域，因为当今地球上使用至少两种语言的人比只会使用一种语言的人还多。对于个人学习者和散居在国外的每个社区来说，第二语言习得都会给他们的语言知识，对不同文化的理解以及个人身份带来挑战。围绕SLA的经验和挑战由学者进行了研究，他们的培训涉及各种领域，例如语言学，心理学，社会学，教育，人类学和传播艺术等，这些都使SLA的研究具有很强的跨学科性。
Second language acquisition (SLA) is the systematic study of learning, using, and sometimes losing any form of language beyond the mother tongue. SLA is a burgeoning research field because today there are more people on the planet who use at least two languages than there are monolinguals. For individual learners and for every community in diaspora, second language acquisition is an experience that challenges their knowledge of language, their understanding of different cultures, and their personal identities. The experiences and challenges surrounding SLA are studied by scholars whose training is in a variety of fields—linguistics, psychology, sociology, education, anthropology, and communication arts—a variety that makes the study of SLA richly interdisciplinary.<br><br>The PhD Program in Second Language Acquisition at the University of Wisconsin–Madison is a rigorous interdisciplinary academic program that embodies the university’s mission to foster the study of globally important issues. n their coursework, students in the program learn from and collaborate with experienced and distinguished faculty in many departments and, through their original dissertation research, students generate and contribute new knowledge to the field. Students develop a thorough understanding of the scope of SLA as a field of inquiry, and develop and refine research skills that will serve them as they define and pursue their own research agenda. A PhD in SLA opens the door to scholarly and professional careers as university faculty, directors of foreign language programs, educational policy makers, and multilingual specialists.