Objectives: This study aimed to provide, for a Jordanian population, the first norms of the faciolingual diameters of the permanent dentition and the mesiodistal diameters of the second molars and to provide and review previously published data on the mesiodistal diameters of the permanent teeth up to the first molars in order to investigate any secular trends. Design: Mesiodistal and faciolingual diameters of the permanent teeth were manually measured on 204 archival pretreatment study casts of adolescents (80 males and 124 females) aged 11–18 years. SPSS (version 16) was used to generate descriptive statistics and investigate the statistically significant differences between right and left sides and between sexes. Results: Males had larger teeth than females, significantly in the mesiodistal dimension and less significantly in the faciolingual dimension. Moreover, in the faciolingual dimension, there was a wider variation in anterior compared with posterior teeth and in males compared with females while the variations were more consistent mesiodistally between anterior and posterior teeth and between sexes. There were some secular trends in the mesiodistal permanent tooth diameters of Jordanians toward a slight reduction and wider variation in tooth size and a slight reduction in sexual dimorphism. Conclusions: The present study has established the first norms of the faciolingual permanent tooth diameters for a Jordanian population which were consistent with corresponding norms that have been published for few other populations. In addition, the present study has provided norms of the mesiodistal permanent tooth diameters of a Jordanian population that are newer and more complete than the previously published norms. It is anticipated that the new norms presented will be utilized in various clinical disciplines of dentistry, in basic dental research, in forensic odontology and in anthropological research.