Government & Defence Entrance Exam

You can become IAS by following processes:
(a) Civil Services Examination: The Civil Services Examination is a nationwide competitive examination in India conducted by the Union Public Service Commission (UPSC) for recruitment to various Civil Services of the Government of India, including the Indian Administrative Service (IAS), Indian Foreign Service (IFS), Indian Police Service (IPS) and others services. Eligibility condition for appearing in civil services examination is as follow:
(I)The candidate must hold a Pass Baachelors' degree from any of the Universities incorporated by an Act of the Central or State Legislature in India or other educational institutions established by an Act of Parliament or declared to be deemed as a University, under Section-3 of the University Grants Commission Act, 1956, or possess an equivalent qualification.
(ii) Candidates who have appeared or intend to appear for the final examination and are awaiting results are also eligible to apply for the Preliminary Examination.
(iii)A candidate must have attained the age of 21 years and must not have attained the age of 32 years.
(Iv)You may refer to UPSC website for other eligibility criterion.
(b) By becoming Public Service Commissions (PCS): Public Service Commissions are the state agency authorised to conduct the Civil Services Examination for entry-level appointments to the various Civil Services of various states. As per Indian Constitution there is provision of provide for a Public Service Commission for each state.
Provincial Civil Services, abbreviated as PCS, are actually the civil based administrative services of the State Government. These officers relate to the policy making of the state to which they belong. These officers are also selected through an entrance test conducted by the state based Public Service Commission. PSC officers are eligible to become IAS after few years of experience by promotion.