Predicates and their Subjects is an in-depth study of the syntax-semantics interface focusing on the structure of the subject-predicate relation. Starting from where the author's 1983 dissertation left off, the book argues that there is syntactic constraint that clauses (small and tensed) are constructed out of a one-place unsaturated expression, the predicate, which must be applied to a syntactic argument, its subject. The author shows that this predication relation cannot be reduced to a thematic relation or a projection of argument structure, but must be a purely syntactic constraint. Chapters in the book show how the syntactic predication relation is semantically interpreted, and how the predication relation explains constraints on DP-raising and on the distribution of pleonastics in English. The second half of the book extends the theory of predication to cover copular constructions; it includes an account of the structure of small clauses in Hebrew, of the use of `be' in predicative and identity sentences in English, and concludes with a study of the meaning of the verb `be'.