  We present results of a binary population synthesis study on the orbital
period distribution of wide binary millisecond pulsars forming through four
evolutionary channels. In three of the channels, the progenitor of the
millisecond pulsar undergoes a common envelope phase prior to the supernova
explosion which gives birth to the neutron star. In the fourth channel, the
primary avoids the common-envelope phase and forms a neutron star when it
ascends the asymptotic giant branch. The four formation channels yield an
orbital period distribution which typically shows a short-period peak below 10
days, a long-period peak around 100 days, and a cut-off near 200 days. The
agreement with the orbital period distribution of observed binary millisecond
pulsars in the Galactic disk is best when the common-envelope ejection is
efficient, the mass-transfer phase responsible for spinning up the pulsar is
highly non-conservative, and no or moderate supernova kicks are imparted to
neutron stars at birth.
