Objectives <p>To evaluate the association between finger dexterity and handwriting proficiency in schoolchildren, and to describe the distribution of pencil grasp patterns during a standardized copy task.</p> Methods <p>This school-based cross-sectional analytical study (June–August 2025) used complete enumeration of students in Grades 3–5. After parental consent, teachers completed the Handwriting Proficiency Screening Questionnaire (HPSQ); students performed a 2–3-line copy task in English for pencil-grasp classification and underwent O’Connor finger dexterity testing under standardized classroom conditions.</p> Results <p>Among 500 students, 170 (34.0%) had poor handwriting (HPSQ ≥ 14). Age, grade, and sex were comparable between the poor and good handwriting groups. Dexterity was markedly worse in the poor handwriting group [O’Connor finger time (s): 388 (71.5) vs. 309.7 (59.9); <i>P</i> &lt; 0.001]. Finger time moderately correlated with HPSQ scores (<i>r</i> = 0.466). Grasp patterns differed between groups (<i>P</i> &lt; 0.001); dynamic tripod was less common in the poor handwriting group (33.5 vs. 50.0%), and non-mature grasps had higher odds of poor handwriting (OR 2.01, 95% CI 1.38–2.93). Poor legibility and performance-time subscores were higher with non-mature grasps and increased with slower finger times. In multivariable analysis, slower finger dexterity and higher grade independently predicted greater difficulty.</p> Conclusion <p>One-third of students had poor handwriting. Slower O’Connor finger dexterity independently predicted teacher-rated difficulty, while non-mature grasp patterns, though more prevalent in poor handwriting group, were not independently predictive. Findings support school screening that pairs HPSQ with a brief dexterity test, with interventions targeting fine motor control rather than grasp retraining.</p>