The BPSC Civil Services Exam consists of three stages:

1. Preliminary Examination:
The preliminary examination is the first stage of the BPSC Civil Services Exam. It is a screening test that aims to shortlist candidates for the main examination. The key details of the preliminary examination are as follows:

- The preliminary examination consists of two papers: General Studies Paper I and General Studies Paper II (also known as the Civil Services Aptitude Test or CSAT).
- Both papers are objective type (multiple-choice questions) and carry 150 marks each.
- The duration of each paper is two hours.
- General Studies Paper I covers topics such as Indian History, Geography, Economy, Polity, Science, etc.
- General Studies Paper II tests candidates' analytical and logical reasoning, comprehension, decision-making, basic numeracy, and data interpretation skills.

Candidates who qualify for the preliminary examination are eligible to appear for the main examination.

2. Main Examination:
The main examination is the second stage of the BPSC Civil Services Exam. It is a written examination that assesses candidates' knowledge and understanding of various subjects. The key details of the main examination are as follows:

- The main examination consists of a total of four papers, each carrying 300 marks.
- The four papers include General Hindi, General Studies Paper I, General Studies Paper II, and an optional subject chosen by the candidate from a list of subjects provided by the BPSC.
- The duration of each paper is three hours.
- General Hindi paper is qualifying in nature and candidates need to score a minimum of 30% marks to qualify.
- General Studies Paper I and II cover topics similar to those in the preliminary examination but in more depth.
- The optional subject paper allows candidates to choose a subject of their interest and expertise.

Candidates who obtain the minimum qualifying marks in the main examination are called for the final stage, which is the interview.

3. Interview:
The interview is the final stage of the BPSC Civil Services Exam. It aims to assess candidates' personality traits, communication skills, and overall suitability for administrative positions. The key details of the interview stage are as follows:

- The interview carries 120 marks.
- It is conducted by a panel of experts who ask candidates a wide range of questions.
- The interview panel evaluates the candidate's mental alertness, critical powers of assimilation, clear and logical exposition, balance of judgment, variety, and depth of interest, ability for social cohesion, and leadership qualities.
- The final selection of candidates is based on their performance in the main examination (900 marks) and the interview (120 marks).

Candidates who perform well in all three stages of the BPSC Civil Services Exam are recommended for appointment to various administrative positions in Bihar.