Our objective was to study the prevalence of different headache types, characterizations, and triggers of headache in Finnish children starting school.Questionnaires were sent to 1,132 families with 6-year-old children. Children with headache disturbing their daily activities (n=96) and an asymptomatic control group of children (n=96) participated in a clinical interview and examination.Children with headache had significantly more bruxism (odds ratio [OR], 1.9; 95% CI, 1.0 to 3.4), tenderness in the occipital muscle insertion areas (OR, 4.8; 95% CI, 1.8 to 12.7), and tenderness in the temporomandibular joint areas (OR, 2.8; 95% CI, 1.3 to 6.0). They also had more travel sickness (OR, 3.4; 95% CI, 1.7 to 6.7) than control children. Eating ice cream (OR, 5.3; 95% CI, 1.4 to 20.3), fear (OR, 3.7; 95% CI, 1.2 to 11.2), and anxiety (OR, 3.2; 95% CI, 1.0 to 10.8) triggered headache more often in migraineurs than in children with tension-type headache. Children with migraine also reported more frequently abdominal (OR, 5.6; 95% CI, 1.7 to 18.1) and other (OR, 3.5; 95% CI, 1.2 to 9.8) pain concurrently with headache, and they used medication for pain relief more often (OR, 3.1; 95% CI, 1.0 to 9.5).Headache classification in children may be improved by palpation of occipital muscle insertions and temporomandibular joint areas, and by discerning a history of triggering events and concurrent symptoms.