Indispensability Argument states that science cannot do without mathematics. Scientists develop theories about the physical world as varied as general relativity, the atomic theory of matter, Darwin's theory of evolution by natural selection and many more. The best of these explain a wide range of empirical phenomena, make accurate predictions, and are widely believed. The Indispensability Argument is regularly said to be the strongest argument for believing in the truth of mathematics. It aims to establish the truth of mathematical claims, and thereby the existence of mathematical objects. In this Element the authors state the argument informally as well as more formally, briefly reviewed its origins, trace some of the philosophical commitments behind the argument's premises, and a more critical evaluation. The argument indisputably relies on naturalism for its plausibility and, more controversially, on confirmational holism.