  We present recent results on scalar light mesons based on Dalitz plot
analyses of charm decays from Fermilab experiment E791. Scalar mesons are found
to have large contributions to the decays studied, $D^+\to K^-\pi^+\pi^+$ and
$D^+, D_s^+\to\pi^-\pi^+\pi^+$. From the first decay, we find good evidence for
the existence of the light and broad $\kappa$ meson and we measure its mass and
width. We find strong evidence for the $\sigma(500)$ meson from
$D^+\to\pi^-\pi^+\pi^+$ decay and measure its mass and width. We also present
the results obtained for the $f_0(980)$ parameters through the $D^+_s
\to\pi^-\pi^+\pi^+$ decay. These results demonstrate the importance of charm
decays as a new environment for the study of light meson physics.
