Polycrystalline garnets of the form (3- x)Y2O3.xGd2O3.5Fe2O3 have been prepared for several values of x ranging from 0 to 3. Lattice constants vary linearly from 12.374+/-0.005 A for yttrium-iron garnet (x=0) to 12.463+/-0.005 A for gadolinium-iron garnet (x=3). Magnetic moments were measured from 77°K to 580°K. For 0<x<0.73, the magnetization decreases as x increases, the decrease being more pronounced at low temperatures. At x~0.73, a compensation point occurs near absolute zero. This compensation point appears at increasingly higher temperatures as x increases beyond 0.73, until it reaches ~287°K for x=3. The magnetic moments for the members of the series show reasonable agreement with values calculated on the basis of the Néel theory.