The introduction of a school management information system (SMIS) in an urban vocational high school, located in a middle-class socio-economic neighborhood, notably affected the learning, behavior and attendance (LBA) interrelations between homeroom teachers (HRTs) and parents. HRT-parents interrelations in general, but those involving parents whose children were having LBA problems in particular, became in most parents' opinion more frequent, more intensive and more formative. Better communication, understanding and trust between parents and the HRTs were observed. Cooperation between home and HRT increased. Implications for the HRT's work are discussed, including a recommendation that HRTs should be trained to use SMIS as a tool for developing and monitoring their interrelations with parents.