This article discusses teachers' use of hand-held computers in a rural New Mexico district to assess student's reading progress. With the help of a federal Reading First grant, the district began using the DIBELS assessments across its elementary schools along with the mCLASS: DIBELS assessment and reporting system. The district's experience helps illustrate the ways educators can use one popular assessment tool to better inform and shape classroom teaching and learning--a concept often labeled "formative assessment." The assessments include thrice-yearly benchmark tests to help screen and group students, as well as more-frequent, one-minute "progress monitoring" measures. Those measures track youngsters' responses to instruction on a particular literacy skill, such as initial sound fluency, phoneme segmentation, reading of nonsense words, or oral-reading fluency. Using the mCLASS: DIBELS assessment system, developed by Wireless Generation, a for-profit company based in New York City, teachers are able to give and record DIBELS results on hand-held computers and get instant feedback. Teachers can then upload the results to the Wireless Generation Web site to track class, school, and district performance over time using online reports.