A one-step rainbow holographic process by using an imaging lens is presented. Results of both the pseudoscopic and orthoscopic rainbow holographic imagings are discussed. One of the most interesting and important applications of the one-step rainbow process is the holographic interferometry. Demonstrations of double exposure, time averaging, and contour generation by this one-step holographic interferometric process are provided. Extension of the one-step process to multiwavelength and multislit holographic interferometry is also included. As compared with the conventional holographic interferometry, the one-step rainbow holograph-ic process is a very simple and versatile technique, which yields the advantages of white light readout. The one-step process offers a brighter image, a lesser speckle noise, and a better fringe visibility. For multi-wavelength and multislit rainbow holographic interferometry, the techniques enable different physical holographic fringe patterns to be displayed in different colors. For multiwavelength technique, they are fringe patterns due to different physical effects, and for multislit technique, they are fringe patterns from different perspectives.