It's really difficult to give you a general answer, because a lot of it depends on where you'd like to get your Ph.D. from. I've created a page called "Test aids for the GRE and GRE Economics" that has quite a few useful links on the GRE General Test. I've found two books rather useful: Econometrics Analysis by William H. Greene and A Course in Econometrics by Arthur S. Goldberger. After doing so, you may want to read the book Public Choice II by Dennis C. Mueller. Although it does have the word "Advanced" in the title, it's more suited for high level undergraduate study. The analytical section is important as well, but the verbal not as much. Romer presents the major theories concerning the central questions of macroeconomics. He teaches at the Richard Ivey School of Business and serves as a research fellow at the Lawrence National Centre for Policy and Management. You should have at least a basic knowledge of differential equations, but you do not have to be an expert in them by any means. Considering a Graduate Degree in History? You do not need to have any knowledge of partial differential equations before entering graduate school, as they are generally only used in very specialized models. A lot of work in subjects such as Political Economy and Public Finance are rooted in "micro foundations" so you'll help yourself immensely in these courses if you're already familiar with high level microeconomics. It is absolutely vital that you score at least 750 (out of 800) on the math section of the GRE in order to get into a quality Ph.D. program. You may also want to look at the Schaum's Outlines - Topology and Schaum's Outlines - Real Analysis. It's as useful as any other undergraduate text I've seen on Econometrics. Books to Study Before Going to Graduate School in Economics. They're also quite inexpensive and have hundreds of useful problems. It has a quite diverse set of topics, all of which are useful tools for economic analysis. Most schools require you to take one or two tests as part of your application requirements. A lot of the material in here is stuff you wouldn't be expected to know entering a program as it's often taught for the first time in Masters and Ph.D. programs. I would suggest buying one of the books on taking the GRE. Reviewing the first few chapters of a book such as Elementary Differential Equations and Boundary Value Problems by William E. Boyce and Richard C. DiPrima would be quite useful. David Romer's "Advanced Macroeconomics, 4/e", continues its tradition as the standard text and the starting point for graduate macroeconomic courses and helps lay the groundwork for students to begin doing research in macroeconomics and monetary economics. There's quite a few good undergraduate texts on Econometrics out there. This is the case in most courses at the Ph.D. level. Hal Varian has a more advanced book called simply Microeconomic Analysis. Your best bet is to see what books are used in the school that you would like to attend. Economics can be a great field in which to do your Ph.D., but you need to be properly prepared before you enter into a graduate program. It is important to study for the test, as it may cover some material that you did not study as an undergraduate. Even if you plan to study a subject which is closer to Macroeconomics or Econometrics, it is important to have a good grounding in Microeconomic Theory. The book is quite difficult in parts so you'll want to have a good background in microeconomic theory before you tackle this one. I would recommend reviewing the book Advanced Macroeconomics by David Romer. There are hundreds and hundreds of different ones available, so I'd suggest looking for one in a second hand shop. David Romer's Advanced Macroeconomics, 4e, continues its tradition as the standard text and the starting point for graduate macroeconomic courses and helps lay the groundwork for students to begin doing research in macroeconomics and monetary economics.