The Test Research and Development Department of the TEPS Center is in charge of the production of TEPS, TEPS-Speaking & Writing, i-TEPS, and SNULT English Test. It also produces customized special English tests according to the requests made by universities, government agencies, training institutions, business corporates, etc. All items are written in accordance with test specifications by internal and external experts who have been trained in item writing. Also, test sets are developed across several review stages, in which internal native-English-speaking researchers and external experts participate. The production of TEPS-Speaking & Writing and i-TEPS, which are computer-based, undergoes extra review stages for optimal test administration.