This textbook/software package covers first-order language in a method appropriate for a wide range of courses, from first logic courses for undergraduates (philosophy, mathematics, and computer science) to a first graduate logic course. The accompanying online grading service instantly grades solutions to hundreds of computer exercises. The second edition of "Language, Proof and Logic" represents a major expansion and revision of the original package and includes applications for mobile devices, additional exercises, a dedicated website, and increased software compatibility and support.