The aim of this study was to develop and critically appraise a global rating scale (GRS) for the assessment of individual paramedic clinical competence at the entry-to-practice level. The development phase of this study involved task analysis by experts, contributions from a focus group, and a modified Delphi process using a national expert panel to establish evidence of content validity. The critical appraisal phase had two raters apply the GRS, developed in the first phase, to a series of sample performances from three groups: novice paramedic students (group 1), paramedic students at the entry-to-practice level (group 2), and experienced paramedics (group 3). Using data from this process, we examined the tool's reliability within each group and tested the discriminative validity hypothesis that higher scores would be associated with higher levels of training and experience. The development phase resulted in a seven-dimension, seven-point adjectival GRS. The two independent blinded raters scored 81 recorded sample performances (n = 25 in group 1, n = 33 in group 2, n = 23 in group 3) using the GRS. For groups 1, 2, and 3, respectively, interrater reliability reached 0.75, 0.88, and 0.94. Intrarater reliability reached 0.94 and the internal consistency ranged from 0.53 to 0.89. Rater differences contributed 0-5.7% of the total variance. The GRS scores assigned to each group increased with level of experience, both using the overall rating (means = 2.3, 4.1, 5.0; p < 0.001) and considering each dimension separately. Applying a modified borderline group method, 54.9% of group 1, 13.4% of group 2, and 2.9% of group 3 were below the cut score. The results of this study provide evidence that the scores generated using this scale can be valid for the purpose of making decisions regarding paramedic clinical competence.