A graph G is completely Positive if every doubly nonnegative matrix realization of G is completely positive. A matrix is SPN if it is the sum of a PSD matrix and a symmetric nonnegative matrix. Let C be a class of square matrices with the property that for every matrix A in C, the principal submatrices of A are also in C. For a graph G with vertices 1, 2, , n a G-partial matrix is an nxn partial matrix whose ij entry is specified iff ij is an edge of G or i=j. The C completion problem is the question of characterizing the graphs G for which every G-partial C matrix can be completed to a matrix in C. In the talk we will show how the solution of the SPN completion problem is related to the characterization of completely positive graphs.