Inclusion:

1. good standing at methadone maintenance program
2. DSM-IV criteria for cocaine dependence or abuse
3. used cocaine at least 4 times in last month
4. able to give informed consent

Exclusion criteria

1. currently meets DSM-IV criteria for Major depression or dysthymia
2. meets DSM-IV criteria for attention deficit hyperactivity disorder, bipolar disorder, schizophrenia or any psychotic disorder
3. history of seizures
4. history of allergic reaction to risperidone
5. chronic organic mental disorder
6. significant current suicidal risk
7. pregnancy, lactation or failure to use adequate birth control (for females)
8. unstable physical disorders that may make participation hazardous
9. coronary vascular disease
10. cardiac conduction system disease as indicated by QRS duration >/= 0.11
11. current use of other prescribed psychotropic medications
12. history of failure to respond to a previous adequate trial of risperidone
13. history of neuroleptic malignant syndrome, tardive dyskinesia, or severe extrapyramidal reactions to neuroleptic medications
14. current DSM-IV criteria for another substance dependence other than nicotine.