It has been observed in many places that constant-factor approximable problems often admit polynomial or even linear problem kernels for their decision versions, e.g., VERTEX COVER, FEEDBACK VERTEX SET, and TRIANGLE PACK-ING. While there exist examples like BIN PACKING, which does not admit any kernel unless P = NP, there apparently is a strong relation between these two polynomialtime techniques. We add to this picture by showing that the natural decision versions of all problems in two prominent classes of constant-factor approximable problems, namely MIN F + 1 and MAX NP, admit polynomial problem kernels. Problems in MAX SNP, a subclass of MAX NP, are shown to admit kernels with a linear base set, e.g., the set of vertices of a graph. This extends results of Cai and Chen (J. Comput. Syst. Sci. 54(3): 465-474, 1997), stating that the standard parameterizations of problems in MAX SNP and MIN F + 1 are fixed-parameter tractable, and complements recent research on problems that do not admit polynomial kernelizations (Bodlaender et al. in J. Comput. Syst. Sci. 75(8): 423-434, 2009).