title: Classroom norms and individual smoking behavior in middle school.
abstract: OBJECTIVE
  To investigate whether smoking prevalence in grade-level networks influences individual smoking, suggesting that peers are important social multipliers in teen smoking.
  
  
  METHODS
  We measured gender-specific, grade-level recent and life-time smoking among urban  middle-school students who participated in Project Northland Chicago in a longitudinal cohort design.
  
  
  RESULTS
  Within schools, grade-level recent smoking had comparable effects on girls' and boys' individual-level smoking. Grade-level lifetime smoking had a greater effect on girls'  smoking.
  
  
  CONCLUSIONS
  Interventions can target middle school classes and schools broadly, without making the identification of friendship networks a concern.
authors.affiliation: Department of Psychology, University of Southern California, Los Angeles, CA, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Yarnell
authors.forename: H Shelton
authors.initials: HS
authors.lastname: Brown Iii
authors.forename: Keryn E
authors.initials: KE
authors.lastname: Pasch
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Perry
authors.forename: Kelli A
authors.initials: KA
authors.lastname: Komro
mesh_terms: D002641:Chicago / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D010379:Peer Group; D015995:Prevalence; D012574:Schools; D012727:Sex Characteristics; D012907:Smoking / Q000453:epidemiology / Q000523:psychology*; D012945:Social Values; D013334:Students / Q000523:psychology* / Q000706:statistics & numerical data