The magnetization process has been studied in arrays of rectangular, electroless plated NiCoP and also evaporated NiFe bars of length L ≃25μ , width W ≃5μ , thickness t, 0.25μ ≤ t ≤ 0.75μ ; and spacing between bars in both the long and short dimensions s = W and also s = 2 W . The principal measurements were H∥ and H⊥, the fields required to magnetize the bars to .75% of saturation in the long and short dimensions respectively versus the product ( M s × t ). Both H∥ and H⊥. increased with ( M s × t ) but H∥ was higher and H⊥ lower than predicted by available calculations. The ratio R = H ⊥ / H ∥ was independent of ( M s × t ) as expected but varied from 4–8 which is lower than theoretical values. The point at which the magnetization no longer increased linearly with field varied from sample to sample and in both directions from 0.3 Ms to 0.9 Ms. No systematic difference in any measurement was observed between arrays with s = W and s = 2 W , so that for these spacings interactions between elements are not significant. Also, the behavior of the NiCoP and NiFe bars was essentially the same. The necessity to develop a model which takes the known domain structure into account is discussed.