  Three-dimensional N-extended superconformal symmetry is studied within the
superspace formalism. A superconformal Killing equation is derived and its
solutions are classified in terms of supertranslations, dilations, Lorentz
transformations, R-symmetry transformations and special superconformal
transformations. Superconformal group is then identified with a supermatrix
group, OSp(N|2,R), as expected from the analysis on simple Lie superalgebras.
In general, due to the invariance under supertranslations and special
superconformal transformations, superconformally invariant n-point functions
reduce to one unspecified (n-2)-point function which must transform
homogeneously under the remaining rigid transformations, i.e. dilations,
Lorentz transformations and R-symmetry transformations. After constructing
building blocks for superconformal correlators, we are able to identify all the
superconformal invariants and obtain the general form of n-point functions.
Superconformally covariant differential operators are also discussed.
