The study investigated how group-dynamics instruction techniques of adaptable nature can be to the benefit of EFL (English as a Foreign Language) learners so as to develop and improve their willingness-to-communicate and speaking-ability in the long run. After analyzing the data via ANCOVA and EFA, the researcher selected 108 young Iranian male and female EFL learners in a language school in Tehran by means of convenient sampling technique. This investigation shows how EFL learners reacted to Group-Dynamics Oriented Instruction (GDOI). Later, the researchers instructed speaking tasks along with improving the learner's willingness to communicate. TOEFL PBT Test was run among participants for homogeneity purposes, and then the researchers used two parallel speaking section of PET test along with WTC questionnaire before and after the treatment process. The findings of the study bore witness to hypotheses of the study, indicating that GDOI was reliably effective in improving speaking ability and uplifting willingness to communicate. In the same line of analysis, the researcher proved that GDOI has improved EFL learner's willingness to communicate since GDOI provoked and triggered energy, interest, and inclination to partake in discussions in learners. As its effects on speaking ability were concerned, the results were interpreted as showing that GDOI would exert changes to L2 learners' conceptual and psychological predispositions that, in return, would determine the strategies and behaviors the learners employ to address the challenges of L2 learning.