Actuarial and economic methods are combined to predict the costs of me
ntal health and substance abuse benefits in insurance. Costs are predi
cted for two employers under alternative benefit plans that contain so
me of the features proposed under national health reform. The cost of
a given benefit differs greatly across population groups. In order to
make accurate cost forecasts, data on the group's experience must be c
ombined with research data on the impact of plan changes. Application
of employers' experience and research from mental health economics can
contribute to better public and private decisions, including those th
at are part of current health reform.