The aim of the study is to find indicators of crowding in primary and mixed dentition that may lead to occurrence of dental crowding in future dentition using dental measurements. A sample of 300 children was selected and divided into two groups based on their age primary dentition and mixed dentition. Dental arch impressions were made and casts were poured. The study was then divided into two phases for assessment of degree of crowding by Little's irregularity index (LII) and by measurement of tooth size-arch length discrepancies. Appropriate statistical analysis was used to assess the correlation of measurements in crowded and noncrowded groups. It was found that Little's index is less dependable as an indicator of anterior crowding. In the primary dentition, there is significant difference in inter-canine width between lower noncrowded and crowded dentition. In the mixed dentition, there is significant difference in Intermolar width between upper noncrowded and crowded dentition and in sum of incisors between noncrowded and crowded dentition in both the arches. Little's index is not a reliable indicator of crowding in both primary and mixed dentition. Inter-canine width of lower arch can be considered as an indicator of crowding in primary dentition. The intermolar width of upper arch, sum of incisors in upper and lower arch and the intercanine width of upper and lower arch can be considered indicators of crowding in the mixed dentition. Kandakkeel FN, Nagar P, Saseendran A, et al. Assessment of Dental Crowding occurring in Mixed Dentition in Maxillary and Mandibular Arches based on Tooth Size-Arch Length Relationships and Certain Cephalometric Parameters. Int J Clin Pediatr Dent 2023;16(2):357-362.