Science educators have been placing much effort in attempting to define and illustrate how scientific inquiry may enhance student learning. Learning through scientific inquiry can be seen as an active process when the individual learner makes linkages between existing ideas and new ones. Self-assessment is one of the ways to promote such an active learning process. When the self-assessment is effective, it becomes a topic of discussion with their teachers and amongst one another, which further promotes reflection on one's own thinking that is essential for sound learning. As teaching, learning and assessment should be coherent, the assessment methods, among which is self-assessment, need to be part of the planning of scientific inquiry tasks. This paper aims at reviewing literature in both fields of self-assessment and scientific inquiry, as well as providing evidence of teacher practice in different countries to define how self-assessment for scientific inquiry actually works. Four examples from an international project called "Schools Around the World" are selected for illustration. These examples were contributed by teachers in the U.S.A., France, Hong Kong, and Japan. Though the nature of inquiry is different in each example, they all adopt certain methods of self-assessment that other teachers may refer to as they design scientific inquiry tasks for their students.