Background: Preschools offer high potential for preventive interventions. However, little is known about the structure of preschool programmes to promote physical activity (PA) in preschoolers although almost all children aged three to six years spend one third of the day at preschool. The aim of this study was to determine whether and to what extent preschools implement systematic PA promotion measures using an instrument specifically developed to assess and systematize preschool PA programmes. Methods: In the cross-sectional study a baseline survey of preschool education policies was conducted to identify and assess the type and extent of PA programmes and opportunities in preschools in the State of Lower Saxony, Germany. An assessment instrument was developed to identify preschools with systematic PA programmes (type 1) and those without PA programmes (type 2) based on the following quality criteria: A) written PA policy, B) structured weekly PA offerings for all children; C) at least one qualified physical education teacher; D) PA-friendly indoor and outdoor facilities (exercise room, situational PA opportunities, outdoor areas, play equipment etc.), and E) structured PA promotion in place for at least two years. A third type of preschool that promotes PA in children to some extent (i.e., that meets the criteria partially but not completely) was classified as "preschools with limited PA programmes". Results: 2415 preschools participated in the survey (response rate: 59%). The results show that 26% (n = 554) have a systematic PA programme while 3% (n = 64) have no PA programme. Most (71%, n = 1514) were classified as limited PA programme preschools. All three types of preschools differed significantly (p = .000) from each other in terms of size (small vs. large). Most of the preschools without PA programmes are small half-day preschools. Conclusions: The study investigated an assessment-instrument providing extensive insight into the nature, extent and routine practical implementation of PA promotion in preschools. The criteria used to evaluate preschool PA programmes are well-suited to identify the different preschool PA programme types and target areas in the field of PA promotion in which specific measures (teacher education, structured PA offerings, etc.) can be implemented in future interventions. (author abstract)