The paper gives a general method for determining the assembly condition of epicyclic gears, irrespective of the structure or gear type. According to the method, an associated mechanism is considered, having a single arm carrier and a split planet. The assembly condition of the gear train is satisfied when obtaining identical superposition of the teeth of the two half-planets after rotating the arm to the next position. By writing simple kinematic relations between some partial transmitting ratios, general formulae are obtained which can be applied to specific epicyclic gear sets as functions of teeth numbers. The same approach allows the determination of the necessary angles between the arms of the carrier, or the offset angles between the wheels of the compound planets, as alternative solutions for the case in which equidistant assembly of identical planets is not possible.