The Coast Guard Reserve Good Conduct Medal was authorized on February 1, 1963. While the eligibility parameters have been modified somewhat over the past five decades, the necessity of the award remains the same: to recognize Reservists who take pride in their work and who realize they represent the Coast Guard whether they’re in or out of their duty uniform.
Just as with the Coast Guard Good Conduct Medal, the overarching requirement for award of the Reserve Good Conduct Medal is been three years of satisfactory service, which the regulations define as “proficiency” in courage, industry, neatness, obedience, rating, and sobriety. The conduct and performance requirements are identical to those of the Good Conduct Medal for active-duty Coast Guardsmen: average marks of three or higher required in all factors and conduct marks of at least four. Any type of misconduct leading to a court-martial or non-judicial punishment automatically wipes away accumulated creditable service, and the member cannot begin accruing creditable service time until either release from confinement or the day following either conviction (in the case of court-martial) or the awarding of the non-judicial punishment.
The Coast Guard used a system of “Retirement Points” to determine eligibility for the Reserve Good Conduct Medal when it was first established, closely mirroring the system the United States Navy had previously employed for its Naval Reserve Medal. This was eliminated in October, 2002, replaced with the requirement of three years of “consecutive” service; air quotes are used because certain breaks in Reserve status, including leaving the service and re-enlisting, do not constitute a break in “continuous” service. Note that Reservists may accumulate creditable service time toward the Reserve Good Conduct Medal while on active duty, so long as that time is not also applied toward the regular Good Conduct medal at a later point.
You can read the other requirements for the Reserve Good Conduct Medal in Chapter 5A2 of COMDTINST M1650.25E located at the CG-612 Directives and Publication Division on the Coast Guard Web site.