The purpose of this study was to identify materials and products in preschools that may contain harmful chemicals and to suggest possible areas of improvement. Another purpose was to examine if a supervisory project focused on chemicals leads to reduced incidence of harmful chemicals and improved routines in preschools. Inspection reports from 46 preschools in Lidingö were examined to see what routines, materials and products that currently existed. The results were compared with inventories of preschools in two other municipalities and a national inventory project. Follow-up questionnaires were sent to 41 of the preschools in Lidingö to examine if the preschools continued to work for a non-toxic environment after the supervision period ended. Preschools at Lidingö showed similar results as the rest of the country, except that the prevalence of old electronics was much lower. Vinyl gloves, soft plastic toys and other plastic objects appeared in more than half of the preschools, and the presence of inappropriate material showed that there is a need for initiatives that promote a non-toxic preschool. The follow-up survey showed that inspections focused on chemicals generally leads to improvements in many areas and can therefore be a good method. The respondents in this study consider the inspectors to be an important support in the process of eliminating harmful substances. Proper cleaning and good purchasing procedures are important to avoid exposure to harmful substances and the removal of phthalates and plastic kitchenware should be a priority for future inspections.