Grounded in complex dynamic systems theory (CDST),this study tracked the development of six English learners’ interactional repertoire in disagreements over thirteen weeks by analyzing two dimensions:turn lengths and disagreement techniques. Dynamic Systems Theory methods including moving min-max graphs and the critical moment method were employed, along with qualitative methods such as conversational analysis. Results show that the two dimensions both experienced non-linear development during the observation period. Firstly, the development of turn lengths varied from person to person and some meaningful variability was found. Secondly, disagreement techniques were diversified, and the development of “direct disagreement”and “agreement / retelling +disagreement”was prior to that of “atypical indirect disagreement”.