The Program in Algorithmic and Combinatorial Thinking (PACT) is a unique educational experience that exposes high school students to theoretical computer science, with a sharp focus on the mathematics and algorithms that form the backbone of the field. While many programs aim to teach students about programming and application development, PACT sets itself apart by offering a theoretical and proof-based approach to computer science training. The curriculum is rigorous and intensive, spanning five weeks of summer. It delves into the intricacies of algorithmic and combinatorial thinking, taking students beyond the surface of computer programming. Participants immerse themselves in tasks such as graph drawing, algebraic expression simplification, and lemma proofing, which are usually not taught until the undergraduate or graduate level. The program is delivered in an engaging, on-site format, where students work in an interactive environment ripe with the excitement of discovery. PACT is run by Professor Rajiv Gandhi, a tenured Professor of Computer Science at Rutgers University-Camden, who also teaches part-time at the University of Pennsylvania. His research interests lie in Algorithm Design, Combinatorial Optimization, and Probabilistic methods. He is joined by a team of distinguished educators from renowned institutions such as the University of Pennsylvania, Northwestern University, Cornell University, and others. These educators bring diverse expertise in areas like Algorithm Design, Combinatorial Optimization, Graph Theory, Communication Complexity, and Algorithmic Game Theory. It is designed for high school students with a keen interest in theoretical computer science. Upon completion of PACT, participants will gain valuable knowledge in algorithmic and combinatorial thinking, preparing them for advanced studies in computer science.