We combine the idea of movement of magnetic flux tubes in the stellar
interiors with the analysis of crustal physics of accreting neutron st
ars in low- and high-mass X-ray binaries to explain the bimodal magnet
ic field distribution of binary pulsars. We propose that this distribu
tion may result from different crustal properties of neutron stars wit
h different accretion sates and amounts of accreted matter. In additio
n, we may provide an explanation for why the magnetic field strengths
of millisecond pulsars with low-mass companions saturate at similar to
3 x 10(8) G when accreted mass exceeds similar to 0.5 M..