AP Computer Science: CSA vs. CSP—Differences, Exam Formats, and How to Prepare

There are two AP Computer Science courses: Computer Science A (CSA) and Computer Science Principles (CSP). Despite their similar names, their content and exam formats differ significantly. CSA is a programming course focused on coding in Java, while CSP is an introductory computing course for non-computer science majors that requires submitting a self-created project. Choosing the wrong one could mean either struggling with the material or getting little help with your college applications.

Based on the College Board website, this article clarifies the differences between the two courses, how to choose, how the exams work, and how to prepare. For the overall AP scoring system, see How to Score a 5 on the AP Exam; for registration and fees, see AP Course Selection and Exam Schedule.

1. Differences Between the Two Courses

How to Choose (Practical Advice): If you plan to major in computer science, software engineering, data science, or related fields, choose CSA, as it tests actual coding skills. If you are interested in computing but do not plan to major in it, or if you have no prior programming experience, CSP offers a gentler introduction. You can take both, or start with CSP and then take CSA.

2. CSA: Java Programming

Exam Format

Fully Digital Exam: Both the multiple-choice and free-response sections are completed on Bluebook. The Java Quick Reference is also available within Bluebook, listing Java library methods that may be used during the exam.

Four Free-Response Questions with Fixed Formats

1. Methods and Control Structures: Write 2 methods (or 1 constructor and 1 method). Part A requires loops or conditional statements, and Part B requires calling String methods;
2. Classes: Design and implement a class according to the specifications, including the class header, instance variables, constructor, and methods;
3. ArrayList Data Analysis: Write 1 method to process data in an ArrayList;
4. 2D Array: Write 1 method to process data in a 2D array.

Four Units and Five Practices

Among the five computational thinking practices, the multiple-choice section has the highest weight for Analyzing Code (37%–53%): determining the output of a piece of code or explaining why it does not run as expected. This is followed by Writing Code (22%–38%).

How to Prepare (Practical Advice)

• Trace Code Manually: Nearly half of the multiple-choice questions involve reading code. Practice tracing code without running the program, writing out variable changes line by line on scratch paper, especially for loops, nested loops, and array indices;
• Master the Four Free-Response Question Types: String methods (substring, indexOf, equals), complete class writing, ArrayList additions, deletions, and traversals (handling index issues when deleting elements during traversal), and 2D array row and column traversals;
• Familiarize Yourself with the Java Quick Reference: Know which methods can be used directly so you don't have to guess during the exam;
• Write According to the Scoring Guidelines: AP Central publishes past free-response questions and scoring guidelines. Compare your answers point by point to see where you lost points.

3. CSP: Introduction + Project

Exam Format

The written responses consist of four sub-questions (Question 1, and Question 2 a/b/c). You can refer to your "Personalized Project Reference" while answering. The three parts of the project must be submitted as final versions in the AP Digital Portfolio by 11:59 PM ET on April 30, 2027.

Five Big Ideas

How to Prepare (Practical Advice)

• Start the Project Early: The 9 hours are in-class time, and April 30 is a hard deadline. The program must include the required elements (such as lists, procedures with parameters, and algorithms). After finishing, make sure you fully understand the code in your "Personalized Project Reference," as the written questions will be entirely about it;
• Familiarize Yourself with the Exam's Pseudocode: The code in the multiple-choice questions follows the language rules in the exam reference sheet, not Python or Java. Review it in advance (for example, note that list indices start at 1);
• Don't Ignore the "Impact of Computing": This section accounts for 21%–26% of the exam, testing topics like privacy, security, the digital divide, and intellectual property. It relies on reading comprehension and understanding, not programming.

4. Score 5 Percentages

One notable trend: the percentage of students scoring a 5 in CSA (25%) is significantly higher than in CSP (10%), but the percentage scoring a 1 in CSA is also as high as 23%, showing a clear polarization. One reason could be the wide variation in programming backgrounds among students taking CSA, so it cannot be simply interpreted as "CSA is easier."

Conclusion

When choosing an AP Computer Science course, consider whether you plan to major in a computer-related field and whether you currently have a programming foundation. The key to CSA is proficiency in both reading and writing code; the key to CSP is starting the project early, fully understanding your own code, and not losing points in the "Impact of Computing" section.

For other AP subjects, see our guides on How to Take the AP Calculus Exam and How to Choose Among the Four AP Physics Courses. If you need AP Computer Science tutoring, feel free to chat with our teachers.

Verification Note: This article was verified against the College Board website in September 2026. The exam structures for both courses, the four CSA free-response question types, the fully digital exam format, the Java Quick Reference, the CSP multiple-choice composition, the Create Task, written responses, submission deadlines, and 2027 exam dates are from the exam pages for both courses on AP Central. The multiple-choice weights for each unit (Big Idea) and computational thinking practice are from the course pages for both courses on AP Central. The equivalent college courses and prerequisite recommendations are from the course pages for both courses on AP Students and the AP Central CSP course page. Score distributions are from the AP Students 2026 Score Distributions page. Course selection advice, details such as the CSP exam pseudocode, preparation strategies, and interpretations of score distributions are our practical recommendations; please refer to the official course descriptions for the current year.

References:

• AP Central: AP Computer Science A Exam
• AP Central: AP Computer Science A Course
• AP Central: AP Computer Science Principles Exam
• AP Central: AP Computer Science Principles Course
• AP Students: 2026 AP Score Distributions