助教（Teaching Assistant，简称TA）指的是在大专院校及中小学内，协助教师教学工作的一种职务。通常助教来自于同领域的毕业生（不一定同校），有些则是由硕士班或博士班研究生兼任、另外也有外聘的。在一些学校，要能升任为讲师及教授、副教授前必需要担任过助教。

在中国大陆的大学中，助教是大学教师的最低一级职称，通常而言，获得硕士学位者如果在大学中获得教席，其首先获得的职称就是助教。

一般而言，助教要做的工作有指导课业、批改学生作业、在系所办公室值班、监考等。在学生数较多的班级，则会于实验课或实习课时协助教师。

A teaching assistant or teacher's aide (TA) or education assistant (EA) is an individual who assists a teacher with instructional responsibilities. TAs include: graduate teaching assistants (GTAs), who are graduate students; undergraduate teaching assistants (UTAs), who are undergraduate students; secondary school TAs, who are either high school students or adults; and elementary school TAs, who are adults (also known as paraprofessional educators or teacher's aides). By definition, TAs assist with classes, but many graduate students serve as the sole instructor for one or more classes each semester as a teaching fellow or graduate student instructor. Graduate and adult TAs generally have a fixed salary determined by each contract period (usually a semester or an academic year); however, undergraduates and high school students are sometimes unpaid and, in the US and other countries with the credit system, receive course credits in return for their assistance. Teaching assistants often help the main teacher by managing students with learning disabilities, such as ADHD, or even physical disabilities, such as blindness or deafness.