This study aims to describe and explain the differences in science process skills and cognitive learning outcomes between students who learn using Project Based Learning (PjBL) and conventional learning in science subjects. This type of research is a quasi-experiment with the matching pretest-posttest control group design. The population in this study is all grade VIII students of SMPN 1 Marga, Tabanan Regency for the 2022/2023 academic year. Research sampling based on class matching techniques. The research instruments are observation sheets of science process skills and cognitive learning outcomes tests. The data in this study is in the form of students' science process skill scores and cognitive learning outcomes scores which are analyzed based on descriptive analysis and the Multivariate Analysis of Covariance (MANCOVA) test. The results showed that:  (1) simultaneously there are differences in science process skills and cognitive learning outcomes between students who learn using Project Based Learning (PjBL) and conventional learning in science subjects, (2) there are differences in science process skills between students who learn using Project Based Learning (PjBL) and conventional learning in science subjects, and (3) there are significant differences in cognitive learning outcomes between students who learn using Project Based Learning (PjBL) and conventional learning in science subjects. The group of students who learned using Project Based Learning (PjBL) showed that science process skills and cognitive learning outcomes in science subjects were superior to the group of students who learned with conventional learning.