  Using 4.8 fb$^{-1}$ of data taken with the CLEO II detector, the branching
fraction for the Cabibbo-suppressed decay $D^+\to\pi^0\ell^+\nu$ measured
relative to the Cabibbo favored decay $D^+\to\bar{K^0}\ell^+\nu$ is found to be
$0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity
constraints, we determine $| f_+^{\pi}(0)/f_+^K(0)|^2=0.9\pm 0.3\pm 0.3$ We
also present a 90% confidence level upper limit for the branching ratio of the
decay $D^+ \to \eta e^+\nu_e$ relative to that for $D^+ \to \pi^0 e^+\nu_e$ of
1.5.
