Florida's law prohibits suspended, deferred, and withheld sentences as well as parole until the minimum 3 years have been served. The study's results indicate that the initial enthusiasm toward the law's ability to reduce crime in Florida has been misplaced. Violent gun crimes did not uniformly decline as predicted. In only one of the nine gun crime series examined was there a significant decline. Alternative theories that would account for these patterns of results and still attribute some deterrent effect to the Florida law are irrelevant here. They make interesting speculations subject to further testing and examining. Overall, Florida's gun law had no measurable deterrent effect on violent crime. This interpretation fits data from both Detroit, another city with a similar gun control law tested for its deterrent effect, and Florida, but it is also plausible. The scope of Florida's law is narrow; it applies only to individuals who actually commit a felony using a gun. In this narrow context, the effect of threatening a 3-year increment in a sentence is minor since the underlying felony already carries the threat of a sentence much greater than 3 years and because the threat of a 3-year sentence is more than offset by the value of the gun in committing the offense and in providing protection. The mandatory sentence would have its greatest deterrent effect on offenders who do not use guns but who might carry one while committing an offense. Although gun control laws carrying mandatory sentences are appealing, evidence suggests that this particular gun control policy does not reduce violent crime. A total of 22 footnotes and tables are included.