Populations of Wood Turtles, Glyptemys insculpta, have steadily decreased over the past 30 yr because of habitat destruction and degradation. We sampled Wood Turtles from three areas in Michigan, USA, to characterize populations, quantify demographic trends, and measure the effect of declining population size on genetic diversity. Wood Turtle samples (n = 68) were collected from three rivers in the Lower Peninsula of Michigan and analyzed at nine microsatellite loci. Bayesian clustering programs identified two populations that split the three sampling sites into North and South populations. In both populations, analysis of genealogies estimated r < 0, indicating population decline. However, no evidence of a bottleneck was detected (P = 0.30 North, P = 0.29 South), and little evidence of inbreeding was observed (average North F_IS = 0.25, average South F_IS = 0.23), relative to other Emydidae populations. The high genetic diversity observed in the North and South populations is likely due to immigration between the two populations (F_ST = 0.04), coupled with the long life span of the Wood Turtle. The conflicting signals suggested from the genealogy models compared to the F_IS and bottleneck analysis suggests that coalescent models may be better suited to detect population decline than other measures of genetic diversity in long-lived species such as the Wood Turtle.