This course builds upon the foundation established in Quantum Theory of Solids I, where the focus was on single-particle physics, including band theory. After a brief review of the topics covered in QTSI, the focus of QTSII shifts towards the exploration of strongly correlated systems characterized by significant electron-electron interactions. This advanced course delves into the profound consequences of such correlations, leading to the emergence of various phenomena. Topics covered include effects of electron-electron interactions in mean field approximations, distinguishing between band and Mott insulators, examining metal-insulator transitions, unconventional metals, exploring magnetism and magnetic materials, understanding model Hamiltonians, and studying superconductors. Students undertaking this course are expected to possess a solid background in quantum mechanics, statistical mechanics, and Quantum Theory of Solids I. By the conclusion of the course, students are anticipated to have developed a robust understanding of the effects of strong correlations in solid-state materials, enabling them to analyze and interpret complex phenomena encountered in condensed matter physics.