This paper presents the history of theStallings Observation System (SOS) and describes theadaptation of the SOS instrument, training for its use ininternational settings, and results from four countries ofthe World Bank International Time on Task (ITOT) project.The ITOT project had three major goals: 1) to discover howinstructional time is used at different levels in certaincountries, particularly in rural and low income areas; 2) toidentify obstacles to optimal use of instructional time; and3) to encourage governments to take the necessary measuresto provide students with optimal time for learning (Abadzi,Millot, & Prouty, 2004). In order to address ITOT at theclassroom level, a pilot study in Tunisia was conducted thattargeted four related objectives: 1) adaptation of theStallings snapshot observation instrument for use in projectclassrooms; 2) design and implementation of training forobservers; 3) determination of reliability and validity ofobservation procedures; and 4) generation of a sampleprofile of classrooms in a Tunisian elementary school. Thispaper summarizes the training and findings from the initialpilot study of time usage at the classroom level conductedin Tunisia in January, 2004 and the training and resultsfrom subsequent ITOT studies in four countries: Tunisia,Morocco, Ghana, and Brazil. More specifically, sections ofthe paper provide an overview of the research on effectiveuse of instructional time using the Stallings instrument,description of the adaptation of the Stallings Snapshotobservation instrument for use in the project, a summary ofthe training and procedures developed for the pilot studyand implemented in four countries, and the results andconclusions from the observational studies in four countries.