Handwriting difficulties may signal dysgraphia or other writing difficulties that can affect literacy performance. Existing instruments measure different handwriting features to identify students for interventions but can take extra testing time and restrict potential indicators appropriate for evaluating adolescents. This exploratory study aimed to evaluate an ecologically valid approach to handwriting assessment. Writing samples from 100 juvenile offenders in Grades 6-12 were gathered at their entry into four long-term secure care facilities in the U.S. state of Georgia and evaluated for nine types of handwriting irregularities. Error scores were tallied across the criteria and descriptively analyzed to determine the central tendencies by criterion and relations among criteria. Summed error scores and reading ability scores were moderately correlated (r = -0.315, p = 0.002). Summed errors also were converted to z-scores, identifying 10% of students with error scores between 1 and 1.999 standard deviations above the z-score mean, and 3% of students with errors =2 standard deviations above the mean. This research offers insights into feasibly and authentically assessing handwriting in diverse settings, aiding the identification and support of adolescents with potential difficulties.