2026 International Conference on Artificial Intelligence for Science (AI4Science 2026) is a premier forum bringing together AI researchers, domain scientists, engineers, and industry practitioners to advance the use of artificial intelligence across the natural and social sciences. The conference emphasizes bidirectional impact: (1) how AI methods unlock new scientific discoveries, simulations, and instruments; and (2) how scientific principles, data, and constraints drive the next generation of reliable, interpretable, and efficient AI. AI4Science features a single-track main program, workshops, tutorials, a datasets/benchmarks track, demos, a doctoral consortium, and a reproducibility & artifacts initiative.