Results for a doped three-leg t-J ladder obtained using the density-ma
trix renormalization group are reported. At low hole doping, the holes
form a dilute gas with a uniform density. The momentum occupation of
the odd band shows a sharp decrease at a large value of k(F) similar t
o the behavior of a lightly doped t-J chain, while the even modes appe
ar gapped. The spin-spin correlations decay as a power law consistent
with the absence of a spin gap, but the pair-field correlations are ne
gligible. At larger doping we find evidence for a spin gap and as x in
creases further we find three-hole diagonal domain walls. in this regi
me there are significant pair-field correlations and the internal pair
orbital has d(x2-y2)-like symmetry.