The purpose of the present study was twofold: (a) to examine the unidimensionality of phonological abilities in Greek, a language with a transparent orthography, and (b) to compute the reliabilities and test the construct validity of a comprehensive phonological battery that was developed to operationally measure and conceptualize phonological abilities in Greek. A secondary focus was to examine gender differences in phonological abilities. The dimensionality of phonological abilities in Greek was examined longitudinally among 280 Greek-Cypriot school children (141 boys and 139 girls) from kindergarten to grade 1. A scale of 10 tasks composed of 140 items tapping phonological skills at syllabic and phonemic levels was used to measure phonological skills. Both exploratory factor analysis at the item level and Rasch modeling (WINSTEPS; Linacre & Wright, 2003) were used to examine the dimensionality of the phonological scale. The results of both analyses indicated that performance on these tasks was represented by a single latent construct. The infit and outfit indices demonstrated the scale's good fit with a 1-parameter item response Rasch model. The separation index for both person and items was higher than 0.95, indicating that the separability of the scale was also very good. Reliability analysis yielded the same results. Further, the results of the present study did not provide any support for gender differences in phonological abilities in the first years of schooling. Overall, this study provides converging evidence for the underlying developmental view of phonological sensitivity as a single ability, especially in a language with a transparent orthography.