The stochastic frontier approach with heteroscedasticity and non-monotonic effects proposed by Wang (2002) is applied to evaluate regional recycling efficiency and to simultaneously estimate coefficients of the factors of inefficiency. There are three input variables, one output variable, and six exogenous determinants of twenty-three municipalities in Taiwan from 1998 to 2004. The average recycling performance has improved progressively. Taichung City is the best performer and Chiayi City is the worst. Municipalities with a higher proportion of highlyeducated population, higher household income, and more promoting activities have better recycling performances. Proportions of high-educated people, household income, and promoting activities have decreasing marginal effects while population density has increasing marginal effects on recycling efficiency. In later periods, only an increase in household income and a decrease in population density significantly help reduce regional recycling inefficiency.