The National Center for Education Statistics (NCES) has explored the feasibility of adjusting nonstandard dropout reports to make them comparable with those from states using the standard Common Core of Data (CCD) definition. Between 1997 and 1999 staff from NCES and state education agencies worked with analysts from Westat to develop a methodology for adjusting nonconforming dropout data and to test a proposed high school completion rate. The analyses presented in this report find that the major types of nonstandard dropout reporting practices have statistically significant, but different, effects on the size of state dropout rates. The most common variant used a reporting calendar that takes a "snapshot" count of dropouts at the conclusion of the school year rather than the beginning. This typically leads to a small net increase in the number of dropouts reported, compared with the CCD reporting guidelines. This report recommends that data from states using an alternative calendar be published without adjustment, with data from states that conform to the CCD reporting calendar and a footnote to identify alternative reporting calendars. This would add 12 to the number of states with dropout data reported by the NCES. The effects of variations regarding the reporting of summer dropouts and the status of those moving to adult education are more variable, and it is recommended that NCES continue to withhold publication of data from states with these variations (10 states in 1995). Appendixes contain dropout and complete definitions and a map of Census regions. (Contains 12 tables.) (SLD)