The purpose of this study was to investigate the effect of a proposed blended project-based learning program on developing the 4cs skills (critical thinking, creative thinking, communication, and collaboration skills) for secondary stage students. The study employed the one-group pretest-posttest quasi – experimental design. The participants were 30 first year secondary stage students at Hassan Abu Bakr Distinguished Governmental Language School in El-Qanater Elkhairya Educational Administration in Qualybia Governorate. The instruments of the study included a list of critical thinking skills, a list of creative thinking skills, a list of communication skills, a list of collaboration skills, a critical thinking test, a pre- post creative thinking test, an observation checklist for communication skills and an observation checklist for collaboration skills. The pre/post critical thinking test, the creative thinking test, and the observation checklists for both communication and collaboration skills were pre administered to the study group. Then, the study group was trained through the proposed blended project-based learning program to develop the 4 Cs skills (critical thinking, creative thinking, communication, and collaboration). The measurement instruments of the study were post administered to the study group. Findings of the study revealed that the blended project-based learning program proved to be effective in developing the 4Cs skills for the study group.