The aim of the present study was to compare the behavioral effects of modafinil, an atypical psychostimulatory acting and cognitive-function improving drug, with the effects of the psychostimulants methamphetamine (MET) and MDMA (3,4-methylenedioxymethamphetamine, or “ecstasy”) in a model of mouse agonistic behavior. This model enables the observation of ethologically well-defined sociable, timid, aggressive, and locomotor behavioral acts and postures. Singly-housed male mice (isolates)were separated into 4 groups. The observations were performed in 4 sessions, 1 week apart. In each interaction, singly-housed mice were paired with nonaggressive group-housed partners for 4 min in a neutral environment. The isolates received, in a Latin square design, either a) a vehicle or modafinil at doses 2.0, 10.0, or 50.0 mg/kg; or b) a vehicle or MET at doses 1.0, 5.0, or 10.0 mg/kg; or c) a vehicle or MDMA at doses 2.5, 10.0, or 30.0 mg/kg. The isolates were categorized as timid or aggressive according to their behavior in the control interaction (vehicle pre-treatment). Elements of locomotor, sociable, aggressive, and timid behavior were evaluated (one-way ANOVA).