By selecting two identified oppositely-charged kaons from a sample of Υ (4S) **data** and subtracting the combinatorial and continuum background, we measure the average multiplicity of φ mesons in B meson decays. Our measurement of B(B → φX) = (3.41 ± 0.06 ± 0.12)% is consistent with both previous measurements at the 1.5σ level, although it is significantly more precise.