Polydrug use increases the likelihood of physical and psychological damage and is linked to a greater likelihood of risk-taking and aggressive behavior. Secondary school students (12 to 16 years old) were studied because substance use is initiated then and preventive interventions can be used. The following research questions were posed: (1) what polydrug use patterns could be discerned among secondary school students; (2) what were the number of students per user type; and (3) what were the corresponding social demographic risk profiles. Data were used from the 1999 National School Survey on Substance Use questionnaires. Polydrug use was defined as the use of two or more substances by one person in the 4 weeks preceding the study (concurrent polydrug use) and the use of several substances on the same occasion (simultaneous polydrug users). The substances included alcohol, tobacco, cannabis, ecstasy, amphetamines, heroin, and cocaine. Results show that almost one quarter of all students, abstainers included, were polydrug users. With regard to the students that used one or more substances, almost one half were polydrug users. “Ordinary” polydrug use (only alcohol and tobacco) was the most common type. This was followed by “soft” polydrug users (alcohol or tobacco combined with cannabis). “Hard” polydrug use (alcohol, tobacco or cannabis combined with a hard drug) was prevalent among the least amount of students (21,000 out of 1,000,000). The risk of belonging to one or another type of polydrug user increased with increasing age, was largest for ethnically Dutch students, very small among Moroccans, limited among Turkish and Surinamese students, and seemed concentrated mainly in the lower educational school types. Boys, compared with girls, had a specific risk of becoming a soft or hard polydrug user. However, the risk of becoming an ordinary polydrug user was equal for both sexes. 1 figure, 4 tables, 26 references