To help secondary school learners overcome the difficulties they encounter when working on their English school projects, we have used one of the cooperative learning techniques Group Investigation (GI), based on the Sharan and Sharan (1992) Model. After applying the model, we wanted to determine the students' attitudes towards project work and the new teaching method. Thus, this research study aimed to measure the effect of the Group Investigation technique on the students' attitudes towards English projects in general and Group investigation in particular. We hypothesize that the GI model will positively affect the students' attitudes and motivation towards their school English projects. To reach the aim of this descriptive quantitative study, we developed a four-section attitude scale, and the current situation is described by analyzing the data obtained from the applied scale. The study's sample is a focus group of 21 students studying at Elhachemi Bouzidi Secondary School in Khenchela, Algeria. The research data were collected, coded, and analyzed using the statistical package for social sciences (SPSS 24.0 Packet program). The researcher also used Cronbach's Alpha to measure the scale's reliability. The research findings reveal that the applied model positively influenced the students' attitudes, project performances, motivation, target language use, and cooperation.