Parentheticals, information that is not directly relevant to the topic being addressed, appear in all academic lectures and help listeners distinguish important from less important information. Their use is a critical skill for all teachers. Despite their importance, research on parentheticals in teaching is scarce. This chapter explores the instructional discourse of native English-speaking teaching assistants and international teaching assistants regarding the use of parentheticals, primarily in terms of the intonational and informational patterns they exhibit. Our analysis involved discourse data collected from sixteen classes, eight from chemistry (four taught by native English-speaking TAs and four taught by ITAs) and eight from English (also four taught by TAs and four by ITAs). While our study suggested that parentheticals can be used to connect the teacher and students interpersonally, and to break up the density of the lecture, we uncovered interesting differences between TAs and ITAs.