Background: Treatment intensity is an important factor in designing and delivering treatments to children with language impairment (LI). However, to date very little is understood about cumulative intervention intensity for children with LI in the US public school system. Aims: To examine treatment intensity (dose: time spent on language; frequency: number of sessions; duration: one academic year) as delivered to children with LI within US public schools and to explore its relation to children's language outcomes. Methods & Procedures: A total of 233 children with LI on the caseloads of 73 speech-language pathologists (SLPs) participated. Direct child measures, weekly treatment logs and videotapes were collected to characterize children's language outcomes and treatment experiences. Outcomes & Results: Children on average received 36 min of treatment during 1.3 treatment sessions per week. Children's language severity did not predict children's treatment intensity. Structural equation modelling indicated a significant interaction between frequency and dose of treatment: children receiving high frequency and low dose, or low frequency and high dose treatment had better outcomes than children receiving high frequency, high dose or low frequency, low dose treatment. Conclusions & Implications: Findings suggest that more intensive language treatment, measured as time, is not necessarily associated with better treatment outcomes.