The current study examined the effects of text-based relational (i.e., cohesion), propositional-specific (i.e., lexical), and syntactic features in a source text on subsequent integration of the source text in spoken responses. It further investigated the effects of word integration on human ratings of speaking performance while taking into consideration individual characteristics in test-takers (e.g., listening proficiency, age, grade point average, working memory capacity) and test-taker strategy use (e.g., note-taking strategies). A total of 263 test-takers' speaking samples were collected using TOEFL-iBT research forms of integrated listen/speak items. This data and, individual characteristics measures and note-taking data were collected over two days. These spoken samples were transcribed and analyzed in terms of textual integration at lexical, cohesion, and syntactic levels. The linguistic features along with the individual characteristics and note-taking data were used to predict human scores of speaking proficiency. The results indicate that the linguistic properties of the source text are almost perfect predicators of which words test-takers will integrate into their response. Moreover, it was found that text integration is an important factor that affects human ratings of speaking proficiency that goes beyond individual test takers' characteristics and note-taking strategies.