In 1998 we wrote a paper describing DNA-based methods for estimating and monitoring both census (Nc) and effective (Ne) population sizes in natural populations (Schwartz, Tallmon & Luikart, 1998). The purposes of this paper were: (i) to review some relatively unexplored, but promising ways that multi-locus genetic data can be used to monitor and detect population declines, (ii) to encourage further development and validation of recent DNA-based Nc and Ne estimators. These approaches are urgently needed to help detect natural population declines in their early stages, so that management actions can be taken to avoid population endangerment and subsequent extinction. Crandall, Posada & Vasco (1999) have criticized the Ne portion of our review claiming that we: (i) excluded phylogenetic estimators of Ne that employ coalescent theory, (ii) did not distinguish between historical and current estimates of Ne, (iii) did not define which Ne we were estimating.