In welfare economics, a social planner is a decision-maker who attempts to achieve the best result for all parties involved. In neo-classical welfare economics, this means the maximization of a social welfare function. In modern welfare economics, there is a greater emphasis on Pareto optimality, in which no one's economic status can be improved without worsening someone else's. Pareto-optimal solutions are not unique, and according to the Second Fundamental Theorem of Welfare Economics, a social planner can achieve any Pareto-optimal outcome by an appropriate redistribution of wealth by means of competitive market.
In practice, the social planner role is generally played by a government entity. However, real governments have multiple goals in addition to, or instead of the benefit of their people. This problem is studied in public choice economics.
 The close connection that exists between the social planning problem and the competitive equilibrium.The first welfare theorem tells us that if an allocation and a set of prices constitute a competitive equilibrium, then the allocation ·will be Pareto efficient . This tells us that the competitive equilibrium is efficient; the only option we have is to redistribute endowments in order to achieve a different point on the contract curve, but there is nothing more we can do. The second welfare theorem, tells us that any social planning problem can be decentralized as a competitive equilibrium.
The welfare theorems establish a connection between the competitive equilibrium and the social planning problem. The welfare theorems also have practical implications.
 This is professional planning work in the areas of social services planning and/or city-wide recreation planning in a multidisciplinary team environment. Employees of this class are responsible for providing community based agencies with social consultative and monitoring services as it relates to the development and administration of preventive social services programs or low income and social housing, and/or conducting socioeconomic evaluations, planning and developing innovative strategies for city-wide social and.
Working as social planner has an emphasis on the development of social policy documents and the management of preventive social service funding programs based on the results of community needs assessments and evaluation studies. Work involves collaboration and partnership with diverse community groups. Employees work with considerable independence and initiative in the funding, consultation and implementation of service initiatives consistent with municipal priorities and/or provincial requirements.
Work involves the effective long-range planning and co-ordination of programs and projects to meet the social needs and aspirations of community services provided throughout the city. Incumbents may be required to act as a Project/Team Leader or Contract Manager and provide advice and direction to consultants or other professional staff. Work can be performed under strategic guidance; results can be evaluated through consultation with a superior for conformance with municipal policy and procedures, and through the implementation of reports and recommendations.