  The scalar form factors for the pions and kaons are calculated in SU(3)
Chiral Perturbation Theory at order $p^6$, in the isospin limit
$m_u=m_d=\hat{m}$. We find in general sizable corrections of
$\mathcal{O}(p^6)$. We use our results to obtain results on the $1/N_c$
suppressed low energy constants $L_4^r$ and $L_6^r$ as well as on two
$\mathcal{O}(p^6)$ low energy constants. We present some numerical results for
masses and decay constants as well.
  We derive a relation for the scalar form factors analogous to Sirlin's
relation for vector form factors.
