The purpose of this paper is to provide researchers and practitioners with valid guidelines for the development of CALL materials for foreign language learning. Our primary goal is to portray how theoretical principles from different language teaching approaches (such as Task Based Language Teaching and Cooperative Learning) can be put into practice efficiently in the design of activities for online (e-learning) and mixed (b-learning) environments. Bearing this in mind, we examine empirical evidence in order to determine the efficiency of Blended Learning vs. face-to-face instruction for English as a Foreign Language Teaching. Both methods were contrasted and tested in an experimental prepost-test control group research design. Findings suggest that the experimental group, which employed a Blended Learning model, had a considerable language improvement compared to the control group that used a traditional face-to-face method. Considering the results, we strongly recommend researchers and practitioners to include Blended Learning models into the design of CALL materials.