  We present the first measurement of $\Upsilon(4S)$ decays to
$\pi^+pi^-\Upsilon(1S)$ and $\pi^+pi^-\Upsilon(2S)$ based on a sample of
230$\times10^6$ $\Upsilon(4S)$ mesons collected with the BABAR detector. We
measure the product branching fractions ${\cal B}(\Upsilon(4S)\to
\pi^+pi^-\Upsilon(1S))\times{\cal
B}(\Upsilon(1S)\to\mu^+\mu^-)=(2.23\pm0.25_{stat} \pm0.27_{sys})\times 10^{-6}$
and ${\cal B}(\Upsilon(4S)\to \pi^+pi^-\Upsilon(2S))\times{\cal
B}(\Upsilon(2S)\to\mu^+\mu^-)=(1.69\pm0.26_{stat}\pm0.20_{sys})\times 10^{-6}$,
from which we derive the partial widths $\Gamma(\Upsilon(4S)\to
\pi^+pi^-\Upsilon(1S))=(1.8\pm0.4)$~keV and $\Gamma(\Upsilon(4S)\to
\pi^+pi^-\Upsilon(2S))=(2.7\pm0.8)$~keV.
