The social skills in a team environment is one of the most important variables related to group effectiveness in cooperative learning situations. In this research we have set two objectives: First, building a Questionnaire of Social Skills Learning Teams (CHSEA in Spanish) in a university context and analyzing its psychometric properties. Secondly, we aim to demonstrate how teamwork with cooperative learning techniques influences the social skills in a team. This research involved 1040 students aged 18 to 44 years from a Spanish University. Three factors of the CHSEA were obtained through various factor analysis and structural equation analysis: “Self-assertion skills”, “Skills of information reception” and “Skills of information production”. We can point out the CHSEA has very acceptable psychometric characteristics, adequate convergent and nomological validity. The latent variables in the three factors found are well defined. The multigroup analysis supports the equivalence of the factorial structure of CHSEA by gender. Finally, we verified that teamwork with cooperative learning techniques influences the social skills of the team and these serve as input to be effective in other cooperative work.