All papers that you write for the next five years, and possibly the rest of your life, should have the following basic format. While different contexts require alterations, you should deviate only with good reason. Alter or leave out some component only when you're convinced it is necessary. Like all rules of thumb, these guidelines have useful purposes, but they should not be treated as iron laws.

The format that follows is appropriate for a paper that applies a theoretical idea to a particular question. Other types of papers (e.g., pure theory) require some adjustments. Part of the point of these rules is to get you to think about the design and structure of your papers wholly apart from the arguments in them. With rare exceptions, papers do not write themselves. Transforming a good idea into a good paper is a difficult process. A clear understanding of what each part of your paper must accomplish is essential to this process.

The philosophy underlying this format is that papers are often their own worst enemies, that their structure and content impede rather aid the reader's understanding of the main point. This is especially true in circumstances where most readers do not read the paper carefully.¹

The first rule of all papers is therefore:

 Part I: Introduction.  From a design point of view, the introduction to a paper is one of its most important parts. A reader that is confused by the introduction or who fails to see that the paper deals with an important or interesting issue is not likely to read the rest. And, if she does read on, she is less likely to get the main point. As a consequence, every introduction must consist of four parts:

Applied papers should not develop a theory for its own sake. Rather, the purpose is to develop just as much as needed to solve the problem posed in the introduction (the actual solving takes place in the next section). As a consequence, this section should not contain all the implications of the approach you've derived; provide only those needed to make the main point of the paper. Even if your theory is very rich, be sparse with your asides and additional implications.

Part III. Application. This is the heart of an applied paper. Here you must show why your theory is relevant to the problem and demonstrate its analytical leverage. Put simply, this section resolves the problem stated in the introduction.

Part IV. Conclusions. State the main point of the paper. This can be in question/answer form or simply a short discussion of the problem and your answer. "In this paper, we have shown that..." Summarize for the reader what your main insight is and why you were able to do something that no one else has. You may also wish to point out some of the limitations of your argument or some of its additional implications.

^* I call these Caltech rules because I learned them while a graduate student at Caltech from the remarkable group of young professors: Bob Bates, John Ferejohn, Mo Fiorina, and especially Roger Noll.  As they learned to articulate principles of good writing, they taught them to their graduate students.  These notes represent a modest continuation of that tradition.

¹   Put another way:  Thinking of your reader as a graduate student who will pore over and over your paper is a mistake.  In order for your paper to get onto reading lists in courses, it must first be read by your professional peers who rarely read a paper in this manner, especially if it is from someone they have never heard.  And referees for professional journals never read papers in this manner.