Under the Indian constitution, as amended in 1977, each citizen has a fundamental duty to "defend the country and render national service when called upon to do so". However, the three services have always been all-volunteer forces, and general conscription has never proved necessary. Military service has long been deemed an attractive option for many in a society where employment opportunities are scarce. The technical branches of the armed forces, however, have experienced problems with recruitment. Since the 1980s, as a result of the growth and diversification of India's industrial base, employment opportunities for individuals with technical training have expanded substantially. Consequently, fewer trained individuals have sought employment opportunities in the armed services.

The Indian army and navy maintain a combined recruitment organization that operates sixty offices in key cities and towns nationwide. The air force has a separate recruiting organization with twelve offices. Army and navy recruitment officers tour rural districts adjacent to their stations and also draw from nearby urban areas. The air force and the navy draw a disproportionate number of their recruits from the urban areas, where educational opportunities are adequate to generate applicants capable of mastering technical skills. The army also recruits outside India, admitting ethnic Gurkhas (also seen as Gorkhas) from Nepal into a Gurkha regiment.

Initial enlistments vary in length, depending on the service and the branch or skill category, but fifteen years is considered the minimum. The tour of duty is generally followed by two to five years of service in a reserve unit. Reenlistment is permitted for those who are qualified, particularly those possessing necessary skills. The minimum age for enlistment is seventeen years; the maximum varies between twenty and twenty-seven, depending on the service and skill category. The compulsory retirement age for officers also varies, ranging from forty-eight for army majors, navy lieutenant commanders, and air force squadron leaders and below, to sixty for army generals, navy admirals, and air force air chief marshals. On occasion a two-year extension is granted on the grounds of exceptional organizational needs or personal ability.

Candidates have to meet minimum physical standards, which differ among the three services and accommodate the various physical traits of particular ethnic groups. Since 1977 recruiting officers have relaxed physical standards slightly when evaluating the only sons of serving or former military personnel--both as a welfare measure and as a means of maintaining a family tradition of military service.

Educational standards for enlisted ranks differ according to service and skill category; the army requirement varies from basic literacy to higher secondary education. The other two services require higher educational levels, reflecting their greater need for technical expertise. The air force requires at least a higher secondary education, and the navy insists on graduation from a secondary school for all except cooks and stewards. Officer candidates have to complete a higher secondary education and pass a competitive qualifying exam for entry into precommission training. All services also accept candidates holding university degrees in such fields as engineering, physics, or medicine for direct entry into the officer corps.

Enlistment was legally opened to all Indians following independence in 1947. In 1949 the government abolished recruitment on an ethnic, linguistic, caste, or religious basis. Exceptions were army infantry regiments raised before World War II, where cohesion and effectiveness were thought to be rooted in long-term attachment to traditions. Some army regiments have a homogeneous composition; other regiments segregate groups only at battalion or company levels. Others are completely mixed throughout. In general, the army has steadily evolved into a more heterogeneous service since 1947. Regiments raised during and after World War II have recruited Indians of almost all categories, and the doubling of the army's size after the 1962 border war with China sped up the process. The armed forces have made a concerted effort to recruit among underrepresented segments of the population and, during the late 1970s and the early 1980s, reformed the recruiting process to eliminate some of the subjectivity in the candidate selection process. Since 1989 the government has sought to apportion recruitment from each state and union territory according to its share of the population. Both the Indian air force and the navy are now almost completely "mixed" services and display considerable heterogeneity in their composition.