A number of researchers have suggested list-assisted sampling for the selection of telephone households to overcome some of the operational difficulties associated with the Mitofsky-Waksberg methods of random digit dialing (RDD). An advantage of a list-assisted method of RDD is that an equal probability systematic sample of telephone numbers can be selected and the variances of estimates from such a sample are usually lower than from a clustered design like the Mitofsky-Waksberg method. The main disadvantage of the list-assisted method is that it excludes some households from the sample, thus creating a coverage bias in the estimates. This article describes research on the coverage bias for a particular method of list-assisted sampling. The two key determinants of coverage bias are the proportion of households that are not eligible for the sample and the differences in the characteristics of the covered and not covered populations. The results show that about 4 percent of all households are excluded in national samples using this method of sampling. Furthermore, they show that the differences between the covered and uncovered populations are generally not large. The coverage bias resulting from these conditions may often be small.