This study aimed to improve of mathematical communication, mathematical connection and analyze mathematical dispositions of students by using the CORE (Connecting-Organizing-Reflecting-Extending) learning model. The study applied a mixed method with embedded design. The subject were 82 X grade students of high school in Sukabumi, West Java, Indonesia. It divided into 42 students for the experimental group and 40 students for the control group. The research data were obtained through well-structured tests of mathematical communication and mathematical connection, mathematical disposition questionnaires, observation sheets, and interviews. Data analysis used t-test, correlation test, descriptive statistic and qualitative. The results indicated that; 1) the CORE learning model can improve students' mathematical communication and connection skills, 2) the mathematical communication for topic I=76.46; topic II=70.98; topic III=72.87; post-test=74.26; and the mathematical connection for topic I=80.07; topic II=79.98; topic III=75.78; post-test=80.27; 3) mathematical communication and connections of students who learned with the CORE model was better than those used expository learning, 4) mathematical dispositions of students who learned with the CORE model was higher than those used expository learning as well and 5) there were correlation among mathematical communication, mathematical connection and mathematical dispositions.