SIETTE is a web-based adaptive testing system. It implements Computerized Adaptive Tests. These tests are tailor-made, theory-based tests, where questions shown to students, finalization of the test, and student knowledge estimation is accomplished adaptively. To construct these tests, SIETTE has an authoring environment comprising a suite of tools that helps teachers create questions and tests properly, and analyze students' performance after taking a test. In this paper, we present this authoring environment in the framework of adaptive testing. As will be shown, this set of visual tools, that contain some adaptable features, can be useful for teachers lacking skills in this kind of testing. Additionally, other systems that implement adaptive testing will be studied. (Contains 4 figures.)