The results of calculations of exchange interactions are presented for f.c.c and simple cubic lattices assuming an RKKY or Caroli and Blandin type double resonance exchange mechanism. Magnetic ordering temperatures have been determined for ferromagnetic and anti‐ferromagnetic types 1, 2 and 3 arrangements of magnetic moments. The theoretical predictions are correlated with experimental results obtained from measurements on palladium based Heusler alloys, in which the electron concentration may be continuously varied and the magnetic sites may be ordered on an f.c.c or s.c lattice depending on heat‐treatment.