The American Journal of Occupational Therapy 79 Interrater and Intrarater Reliability of the Assisting Hand Assessment OBJECTIVE. The aim of this study was to evaluate interrater and intrarater reliability for the Assisting Hand Assessment. METHOD. For interrater reliability, two designs were used: 2 occupational therapists rated the same 18 chil- dren, and 20 occupational therapists rated the same 8 children. For intrarater reliability, 20 raters each rated one child twice. Both English and Swedish versions of the instrument were used. Intraclass correlation coeffi- cients (ICCs) and standard error of measurement (SEM) were calculated. RESULTS. ICCs for the sum score for the interrater were 0.98 (two raters) and 0.97 (20 raters) and for the intrarater 0.99. SEM was 1.5 for interrater and 1.2 for the intrarater study, which gave an error interval of ± 3 raw scores for interrater and ± 2.4 raw scores for intrarater. CONCLUSION. This study shows excellent interrater and intrarater reliability for sum scores. Holmefur, M., Krumlinde-Sundholm, L., & Eliasson, A.-C. (2007). Interrater and intrarater reliability of the Assisting Hand Assessment. American Journal of Occupational Therapy, 61, 79–84. Introduction Hand skills are vital for the performance of activities in everyday life. The coordi- nated use of two hands is the most efficient way to conduct most activities. Impairments of the upper limbs imply complications in almost all areas of human occupations (Exner, 2001; Sköld, Josephsson, & Eliasson, 2004). Persons with a unilateral impairment (e.g., from hemiplegic cerebral palsy and brachial plexus palsy) have a specific condition, with one well-functioning hand and one hand with different degrees of dysfunction. Something as ordinary as playing with build- ing blocks, dressing a doll, zipping up a jacket, or making a sandwich can be quite difficult to manage one-handed. Probably the most important aspect of hand func- tion for persons with unilateral impairments is how effectively the affected hand is used in the performance of activities in which both hands need to be involved. In hand function assessments used in pediatric occupational therapy services, how- ever, commonly one hand is assessed separately from the other, such as in the Melbourne Assessment of Unilateral Upper Limb Function (Randall, Carlin, Chondros, & Reddihough, 2001), Quality of Upper Extremity Skills Test (QUEST) (DeMatteo et al., 1992), and Jebsen–Taylor Hand Function Test (Taylor, Sand, & Jebsen, 1973). Although some hand function assessments involve the use of both hands (e.g., to cut with scissors or to string beads), it is the time or accuracy of the task that is evaluated, not how the tasks are completed concerning the use and role of an affected hand. The Assisting Hand Assessment The Assisting Hand Assessment (AHA) is a newly developed test with the purpose of measuring and describing how effectively children who have a unilateral dis- ability use their affected hand (assisting hand) in collaboration with the nonin- volved hand during bimanual performance. The AHA was shown to produce valid Marie Holmefur, MSc, Reg. OT, is PhD Student, Neuropediatric Research Unit, Department of Women and Child Health, Karolinska Institutet, Astrid Lindgren Children’s Hospital Q2:07, S-171 76 Stockholm, Sweden; marie.holmefur@ki.se Lena Krumlinde-Sundholm, PhD, Reg. OT, is Researcher, Neuropediatric Research Unit, Department of Women and Child Health, Karolinska Institutet, Stockholm, Sweden. Ann-Christin Eliasson, PhD, Reg. OT, is Associate Professor, Neuropediatric Research Unit, Department of Women and Child Health, Karolinska Institutet, Stockholm, Sweden. KEY WORDS • hand • pediatric • reliability Marie Holmefur, Lena Krumlinde-Sundholm, Ann-Christin Eliasson