The phase of treatment evaluation affirming the general effect of addi
ction treatment seems to be terminated. The present task of evaluation
is the problem, which treatment variables are effective under which c
onditions. Effects of treatment variables were summarized for motivati
on treatments and for short interventions. As to treatment length the
conclusion from different reviews is that longterm treatment is slight
ly more successful than shortterm treatment. But moderator variables a
re most important for allocating patients to different treatment lengt
hs. The effects of other treatment variables were described as empiric
ally based indicators for improving outcome. The treatment of drug add
icts is characterized by the following points: 1. Treatment outcome in
drug addicts is less successful than in alcohol addicts. 2. Applicati
on of medicaments is more important in the outpatient treatment of dru
g addicts. 3. The principles of therapeutic communities are important
influence factors for the inpatient treatment of drug addicts. 4. Low
level treatment and help for basic needs are more important in treatin
g drug addicts than alcohol addicts. Empirical results about the influ
ence of therapist variables about self help groups and about treatment
indication were discussed for both groups of addiction.