  The double-differential production cross-section of positive pions,
$d^2\sigma^{\pi^{+}}/dpd\Omega$, measured in the HARP experiment is presented.
The incident particles are 8.9 GeV/c protons directed onto a beryllium target
with a nominal thickness of 5% of a nuclear interaction length. The measured
cross-section has a direct impact on the prediction of neutrino fluxes for the
MiniBooNE and SciBooNE experiments at Fermilab. After cuts, 13 million protons
on target produced about 96,000 reconstructed secondary tracks which were used
in this analysis. Cross-section results are presented in the kinematic range
0.75 GeV/c < $p_{\pi}$ < 6.5 GeV/c and 30 mrad < $\theta_{\pi}$ < 210 mrad in
the laboratory frame.
