This paper discusses the quantization of electromagnetic fields interacting with nonrelativistic atoms and molecules in the dipole approximation. Quantizing the field variablesDandHand taking the interaction density−ε0−1P·D,we obtain a quantum theory corresponding to classical electrodynamics with no free currents and the induced dipole moments as the only sources of the radiation field. The resulting equations are found to agree with those Power and Zienau obtained from causality requirements. A comparison with the conventional approach is given.