  The spin correlation coefficent combinations A_{xx}+A_{yy} and A_{xx}-A_{yy},
the spin correlation coefficients A_{xz} and A_{zz}, and the analyzing power
were measured for \vec p \vec p --> d pi^+ between center-of-mass angles 25 deg
\leq \theta \leq 65 deg at beam energies of 350.5, 375.0 and 400.0 MeV. The
experiment was carried out with a polarized internal target and a stored,
polarized beam. Non-vertical beam polarization needed for the measurement of
A_{zz} was obtained by the use of solenoidal spin rotators. Near threshold,
only a few partial waves contribute, and pion s- and p-waves dominate with a
possible small admixture of d-waves. Certain combinations of the observables
reported here are a direct measure of these d-waves. The d-wave contributions
are found to be negligible even at 400.0 MeV.
