As per National Education Policy-2020 Common Minimum Syllabus for all U.P. State Universities/ Colleges. This textbook is designed according to the NEP-2020 syllabus for the Classical Mechanics and Statistical Mechanics course. The content is organized systematically, covering a range of essential topics including Constrained Motion, Lagrangian Formalism, Hamiltonian Formalism, Central Force, Macrostate & Microstate, Concept of Ensemble, Distribution Laws, and Applications of Statistical Distribution Laws.