  We have studied the production of B hadrons in 1.8-TeV p-pbar collisions. We
present measurements of the fragmentation fractions, f_u, f_d, f_s and
f_baryon, of produced b quarks that yield B^+, B^0, B^0_s and Lambda_b hadrons.
Reconstruction of several electron-charm final states yields
f_s/(f_u+f_d)=0.213+/-0.068 and f_baryon/(f_u+f_d)=0.118+/-0.042, assuming
f_u=f_d. If all B hadrons produced in p-pbar collisions cascade to one of these
four hadrons, we determine f_u=f_d=0.375+/-0.023, f_s=0.160+/-0.044 and
f_baryon=0.090+/-0.029. If we do not assume f_u=f_d, we find
f_d/f_u=0.84+/-0.16.
