Recently someone asked me for advice on the best prep course to take to help them pass the PMP*. They didn't like my answer: I don't think any prep courses are sufficient, on their own, to enable you to pass the PMP.
Passing the exam requires a mix of knowledge from the PMBOK, and knowledge that really only comes from experience.
*Find out more about the PMP certification from the Project Management Institute.
As far as supporting/prerequisite education I would suggest having at least an introductory level understanding of the following areas/concepts (in no particular order):
- Project procurement and purchasing processes
- Business law/contracts
- HR and recruiting
- Business writing and communications
- Cost benefit analysis
- Budget forecasting models
- Conflict resolution
- Decision making models
- Industry-specific training (based on the industry you are interested in)
- Personnel management
- Organizational management structures
- Quality Assurance
- Stakeholder expectation management
- Principles of leadership and ethics
I'm sure there are plenty areas of focus I have missed, too. And I wouldn't say you have to have an exhaustive knowledge of any of these areas, everyone has their gaps.
The PMP exam is structured to provide a reasonable measure of an individual's ability to apply project management concepts in the real world. It's not perfect, but you can't memorize facts from a book and expect to get the correct answers. Almost every question has more than one correct answer, and the questions are structured to mislead you on purpose (if you aren't paying close enough attention).
If you are at all curious about the kinds of questions on the exam, there is a free bank of questions that I used to study that can give you some insight into the nature of the test:
All of that said, there is no requirement that you earn a PMP to become a project manager. Most of the best project managers I have worked with do not have a PMP.