The philosophy of science has lost its self-confidence, witness the lack of advanced textbooks in contrast to the abundance of elementary textbooks. Structures in Science is an advanced textbook that explicates, updates, accommodates, and integrates the best insights of logical-empiricism and its main critics. This `neo-classical approach" aims at providing heuristic patterns for research. The book introduces four ideal types of research programs (descriptive, explanatory, design, and explicative) and reanimates the distinction between observational laws and proper theories. It explicates various patterns of explanation by subsumption and specification as well as structures in reductive and other types of interlevel research. Its analysis of theory evaluation leads to new characterizations of confirmation, empirical progress, and pseudoscience. Partial analogies between progress in nomological research (i.e. observational, referential, and theoretical truth approximation, presented in detail in From Instrumentalism to Constructive Realism, 2000) and progress in explicative and design research emerge. Finally, special chapters are devoted to design research programs, computational philosophy of science, the structuralist approach to theories, and research ethics.