Early detection of loneliness in children, especially children with special needs who are at greater risk for loneliness, is crucial for planning appropriate interventions. A review of studies regarding the assessment of loneliness in children reveals the Children's Loneliness Scale (CLS) is commonly used in other cultures whereas information about the use of CLS in Turkish culture, especially on children with special needs, is very limited. This study investigates the psychometric properties of CLS on a group of 4th and 5th graders with and without special needs in inclusive classrooms. The study group consists of 554 typically developing students and 151 students with special needs, a total of 705 students whose ages range from 9 to 13. Exploratory factor analysis (EFA) was conducted to examine the construct validity of the CLS and revealed that the scale has a unidimensional structure. The validity of this unidimensional construct was confirmed using confirmatory factor analysis (CFA). Discriminant validity of the CLS was examined using the criterion group method and a significant difference was found between the loneliness scores of students with special needs and those without special needs. Internal consistency and test-retest reliability analyses were conducted in order to determine the reliability of the CLS. Results showed that the CLS has high internal reliability and provides stability in measurements. In general, the findings of this study indicated that the CLS is a valid and reliable instrument for assessing the loneliness levels of students with and without special needs attending 4th and 5th grade inclusive classrooms.