Schroeder's "An Introduction to Thermal Physics" is one of the simplest, most concise, and engaging treatments of the subject matter (classical thermodynamics, classical and quantum statistical mechanics, with applications) that I have ever come across, without sacrificing thoroughness and rigor. The organization, exposition, and development of the book and subject matter is very clear and straight-forward; its introduction of basic ideas, postulates, and applications were sufficient to make accessible those later chapters in which advanced topics were covered. Although a strong mathematical background is required to fully appreciate this book, the author does a rare thing: he carefully and painstakingly connects the mathematics back to the physics of the problem. In undergraduate texts of this level, it is easy to lose oneself in abstractions. This is a pitfall that Schroeder deftly avoids. For this, I strongly recommend "An Introduction to Thermal Physics" for all undergraduate students, even as a supplement to other "authoritative" texts in the field, i.e. Kittel's "Thermal Physics." (An additional boon to undergraduates is the inclusion of worked problems throughout the book, which give guided practice at application of main ideas, as well as subtle tests of one's mastery of the basic underlying theory.)