Objective:Juvenile idiopathic arthritis (JIA) is the most common autoimmune and familial Mediterranean fever (FMF) the most common autoinflammatory chronic rheumatic disease in childhood. We aimed first to identify developmental and behavioral problems of preschool-age children with common chronic rheumatic diseases, second to compare the diagnostic categories, and third to elucidate the associated factors with these difficulties. Method: Of the 91 participants included in this study, 46 were children with rheumatic diseases (27 with JIA and 19 with FMF) and 45 were healthy children. The general developmental and emotional/behavioral problems of each child were evaluated by the Ages and Stages Questionnaire and Child Behavior Checklist-1 1/2-5, respectively. The State-Trait Anxiety Inventory and Beck Depression Inventory were used for maternal well-being. Results: Internalizing problem scores were increased, and the percentage of children who failed at least 1 developmental domain and experienced delays in fine motor and problem-solving domains were higher in children with chronic rheumatic diseases when compared with healthy children. Being in the group of rheumatic diseases, fewer maternal education years and higher screen time were found to be independent risk factors significantly associated with any developmental delay in the multivariable model. Maternal trait anxiety scores were positively associated with internalizing and total problems only in FMF. Conclusion: Preschool-age children with a diagnosis of chronic rheumatic diseases were more vulnerable for developmental and behavioral problems compared with healthy children. The management of chronic rheumatic diseases in the early years should include the screening of developmental and behavioral problems.