Variation in policies virtual schools use to calculate course completion and retention rates impacts the comparability of these quality metrics. This study surveyed 159 U.S. virtual schools examining the variability in trial period and course completion policies--two policies that affect course completion rates. Of the 86 respondents, almost 70% had trial periods that varied from 1 day to 185 days. Course completion definitions varied from remaining in the course irrespective of the final grade to receiving an A- in the course. Such wide variation renders the completion and retention rate metrics useless. We recommend virtual schools adopt consistent measures for calculating student retention to allow meaningful comparisons among virtual schools and between virtual and brick-and-mortar schools. (Contains 8 tables.)