The dipole energy of a lattice of point dipoles in the configurations of the polyamides 6.6 and 6, of tetradecanamide, and of $\alpha$ and $\beta$ forms of poly-L-alanine are calculated. The dipole forces contribute 4$\cdot$8 kcal/mole to the lattice energy of nylon 6.6 of which 93% arises from the collinear arrays of CONH dipoles along the 'a' axis. For nylon 6 the total energy is 4$\cdot$6 kcal mole. In tetradecanamide the total energy is 3$\cdot$9 kcal/mole of which only 0$\cdot$7 kcal/mole arise from the dimer pairs of CONH$_2$ groups. The calculated energy for $\beta$ poly-L-alanine is 5$\cdot$7 kcal/mole but only 1$\cdot$8 kcal/mole for the $\alpha$ helix. The dipole forces only stablize the $\alpha$ helix for molecules containing more than 14 CONH groups. Below this length the dipole energy is repulsive. CO$\ldots$HN hydrogen bonding contributes to the stability of the helix. Changes in configuration of protein molecules from $\alpha$ to $\beta$ forms are probably facilitated by a balance between dipole forces and hydrogen bonding which vary reciprocally with changing configurations of the CONH group contacts.