We introduce a new Macaulay2 package, Nauty, which gives access to powerful methods on graphs provided by the software nauty by Brendan McKay. The primary motivation for accessing nauty is to determine if two graphs are isomorphic. We also implement methods to generate families of graphs restricted in various ways using tools provided with the software nauty. INTRODUCTION. Let G and H be two finite, simple, undirected graphs on the common vertex set V with edge sets E(G) and E(H), respectively. We say that G and H are isomorphic if there is a bijection j from V to itself which preserves edges, that is,fu; vg2 E(G) if and only iffj(u);j(v)g2 E(H). Determining whether two given graphs are isomorphic is known as the Graph Isomorphism problem. When Garey and Johnson wrote their classic book (GJ) on the complexity of algorithms, they specified twelve problems of ambiguous complexity, one of which was the Graph Isomorphism problem. Unfortunately, it is still unknown if the Graph Isomorphism problem is P or NP-complete. Moreover, the problem is of such notoriety that some have even begun referring to a new complexity class, GI, of problems which reduce in polynomial time to the Graph Isomorphism problem (J). Despite this, there exists computer software which is capable of determining whether two graphs are isomorphic in reasonable time. One such piece of software is nauty (N) by McKay. The nauty software is written in highly portable C and is designed to, above all else, compute whether two graphs are isomorphic. It also includes an extensive family of tools, collectively called gtools, to generate systematic modifications of graphs, to generate specific families of graphs, to generate random graphs, to filter a set of graphs for given properties, and to canonically relabel graphs. Most of these features would be beneficial to any computer software that handles graphs. The package EdgeIdeals (FHT) by Francisco, Hoefel, and Van Tuyl implements structures and methods for manipulating graphs (and hypergraphs) within Macaulay2 (M2), a software system by Grayson and Stillman designed to aid in research of commutative algebra and algebraic geometry. We introduce a new package, Nauty, for Macaulay2, which provides an interface with nauty. 1 Most of the aforementioned tools in gtools are accessible through Nauty. In particular, the methods of perhaps the greatest interest are areIsomorphic, filterGraphs, generateGraphs, and generateRandomGraphs. The remainder of this note is broken in to two sections: the first describes briefly the theoretical underpinnings of nauty and the second gives an example session of using Nauty along with a few useful caveats. CANONICAL LABELLINGS. In (M), McKay describes the improved algorithms which he developed to canonically label a graph; these algorithms are the heart of nauty and are summarised in (N). We recall briefly the theoretical ideas which make such algorithms useful.