This study explores the validity and reliability of a school environment instrument supplied to 3160 teachers from Medellin – Colombia public schools in 2011. The multilevel factorial analysis allowed establishing that through 20 reactive, the instrument evaluates four school environment dimensions at individual level: communication from the school to the teachers and communication from the teachers to the parents, participation level into the school decisions, respect-emotional security and academic expectations. At the group level, the same reactive allowed measuring a general school environment dimension. Therefore, results suggested the instrument permits to establish differences between schools in school environment terms.