Breaking down the question
The question has a definitional part and an analytical part. What do you mean by social mobility? asks for a precise conceptual statement, ideally with the standard typology — vertical and horizontal, upward and downward, intergenerational and intragenerational, individual and structural.
The main weight lies in the second command: discuss the major sources and causes of mobility. Here the examiner wants the conditions and mechanisms that produce movement between social positions — economic change, education, occupational transformation, demography, migration, and the openness of the stratification system itself. A good answer distinguishes sources (the structural openings that make mobility possible) from causes (the factors that push or pull individuals through them), though the two overlap.
For the conceptual base, use the note on social mobility.
How to approach it
Open with a tight definition anchored in Sorokin, who first mapped the field, and lay out the typology so the rest of the answer has a working vocabulary. Keep this part proportionate — it is the foundation, not the bulk.
Then devote the greater share to sources and causes, organised thematically rather than as an undifferentiated list: structural-economic factors (industrialisation, occupational shift), education and achievement, demographic and migratory factors, political and legal interventions, and the degree of openness of the system. Use the classic Lipset–Bendix comparative findings to show empirical grounding. Distinguish structural mobility (society-wide shifts) from circulation or exchange mobility (individuals swapping positions). Conclude by relating mobility to whether the system is open or closed, and note the Indian case briefly.
Model answer
Social mobility refers to the movement of individuals, families or groups from one position to another within the system of social stratification. The term and its systematic study owe most to Pitirim Sorokin, whose Social Mobility treated society as a stratified space through which people circulate. Mobility is thus a change in an actor's or group's location in the hierarchy of statuses, and its study asks how much movement a society permits, in what direction, and by what means.
The concept is conventionally classified along several axes. Horizontal mobility is movement between positions of roughly equal rank — a change of occupation or residence without a change of status. Vertical mobility is movement up or down the hierarchy, and is the type of chief sociological interest; it may be upward (a labourer's child becoming a professional) or downward (loss of rank). By time-frame, intragenerational mobility traces an individual's career across her own lifetime, while intergenerational mobility compares the status of children with that of their parents — the standard measure of a society's openness. Finally, mobility may be individual, where a person moves through personal effort or circumstance, or structural (also called forced or collective), where whole strata move because the shape of the occupational structure itself changes.
Turning to the sources and causes of mobility, several interlocking factors must be distinguished.
Structural and economic change. The most powerful source is transformation of the occupational structure through industrialisation and technological change. As economies shift from agriculture to industry and then to services, the proportion of manual jobs shrinks and professional, technical and white-collar posts multiply. This creates structural mobility: children are pulled upward not because they outcompete their parents but because there is more "room at the top". The expansion of the middle class in industrial societies is the classic instance.
Education and achievement. In modern societies education is the principal channel — Sorokin's term for institutional ladders of ascent. The spread of mass schooling and higher education converts ascribed disadvantage into achievable qualification, allowing merit and credential to override birth. Where access to education is unequal, however, the same channel reproduces privilege, so education is both an engine of mobility and a mechanism of closure.
Demographic factors. Differential fertility between strata affects mobility: when higher strata reproduce below replacement while lower strata grow, vacancies at the top must be filled from below, generating upward movement. Changing patterns of marriage (hypergamy, assortative mating) and mortality also redistribute positions across generations.
Migration and urbanisation. Movement from countryside to city, and across regions and nations, loosens people from inherited local hierarchies and exposes them to new opportunities, functioning as both a horizontal and a vertical source of mobility.
Political, legal and reformist intervention. The state can open or close channels. Abolition of legal disabilities, land reform, reservation and affirmative action, and the expansion of public employment all create routes of ascent for previously excluded groups. Revolutions and social movements can effect abrupt collective mobility by dismantling an old order.
The openness of the system itself. Whether these sources translate into actual movement depends on how open or closed the stratification order is. In a closed system — the classic caste order, or a rigid estate — status is ascribed at birth and mobility is minimal; in an open class system, status is at least partly achieved and movement is expected. Value systems matter here: an ethic that legitimises ambition and achievement encourages mobility, whereas an ideology of fixed hierarchy discourages it.
The comparative research of S. M. Lipset and Reinhard Bendix gave these arguments an empirical footing. Studying several industrial nations, they found that the overall rate of mobility across advanced industrial societies was broadly similar and substantial, and argued that industrialism as such — not any single national culture — generates comparable structural mobility by reshaping the occupational pyramid. Their work also clarified the distinction between structural mobility, driven by changes in the number of positions, and pure exchange or circulation mobility, in which individuals merely swap ranks.
In the Indian context, mobility must be read against the historically closed caste system, within which M. N. Srinivas's concept of sanskritisation describes the upward positional mobility of a whole caste through the adoption of higher-caste practices — a distinctively group form of movement. Industrialisation, the spread of education, urban migration and constitutional measures such as reservation have since introduced significant class mobility, even as caste continues to shape opportunity.
In sum, social mobility is the circulation of persons and groups through the stratification order, and its extent is set by the interplay of structural-economic transformation, education, demography, migration and political intervention, all filtered through the degree to which the system is open. Mobility is therefore a sensitive index of a society's fairness, its dynamism and the strength of the link between birth and destiny.
Examiner's perspective
Examiners look first for a controlled definition and an accurate typology — vertical/horizontal, inter/intragenerational, individual/structural. Scripts that muddle these or omit the intergenerational measure lose the conceptual base.
The higher marks turn on the second command. Strong answers organise the sources and causes thematically and, crucially, distinguish structural mobility from circulation mobility — the single most rewarded analytical point. Naming Sorokin for the framework and Lipset and Bendix for the comparative evidence signals reading beyond the textbook, as does linking mobility to the open–closed continuum.
A common weakness is an unstructured list of causes with no hierarchy and no Indian illustration. The best thirty-mark answers are proportioned — compact definition, substantial and classified discussion of sources, a comparative and an Indian reference (sanskritisation) — and close by treating mobility as a measure of the society's openness.