We evaluated the technical adequacy of oral reading fluency (ORF) probes in which 1,472 middle school students with and without reading difficulties read fluency probes for 60 s versus reading the full passage. Results suggested that the reliability of 60-s probes (rs = 0.75) was not substantively different than full passage probes (rs = 0.77) among struggling readers and typically developing readers in Grades 6 to 8. The correlation of 60-s and the full passage probes with norm-referenced measures of ORF ranged from 0.32 to 0.83, and the correlation with norm-referenced measures of reading comprehension ranged from 0.32 to 0.54, indicating that both measures were moderately valid and adequate for use among middle school students. Last, full passage probes with sensitivity rates ranging from 0.40 to 0.45 were only slightly more sensitive for identifying at-risk readers than 60-s probes, with sensitivity rates ranging from 0.36 to 0.40, suggesting that the full passage probes identified a slightly higher percentage of at-risk students with reading difficulties.