We present a preliminary measurement of the rate of gluon splitting into bottom quarks, <i>g</i> --> <i>b anti-b</i>, in hadronic <i>Z</i><sup>0</sup> decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavor. 4-jet events were identified, and a topological vertex-mass technique was applied to each jet in order to identify <i>b</i> or <i>anti-b</i> jets. The upgraded CCD based vertex detector gives very high <i>B</i>-tagging efficiency, especially for <i>B</i> hadrons of the low energies typical of this process. The two most nearly collinear <i>b</i> / <i>anti-b</i> jets were tagged as originating from <i>g</i> --> <i>b anti-b</i>. We measured the rate of secondary <i>b</i> / <i>anti-b</i> production per hadronic event, <i>g<sub>b anti-b</sub></i>, to be (2.84&#177;0.61(stat.)&#177;0.59(syst.))x 10<sup>-3</sup> (preliminary).