This paper examines the optimal use of criminal solicitation as a law enforcement strategy. The benefits are greater deterrence of crime (due to the greater likelihood of apprehension), and the savings in social harm and apprehension costs as some offenders are diverted away from committing actual crimes through solicitation. The costs are the expense of hiring undercover cops and the greater likelihood of punishment. The optimal use of solicitation balances these factors. The paper also examines the justification for, and impact of, the entrapment defense, which exonerates those caught in a solicitation but otherwise not predisposed to commit a crime.