The Upper Limb Performance Assessment is an ecologically valid, criterion-referenced, two-stage assessment of upper limb contributions to task performance and the biomechanical/motor actions impacting on task performance (Ranka, & Chapparo, 2011).  Stage one, Task Performance Mastery (TPM), is used to analyze and assess the degree to which a person can perform the motor steps of any needed or desired task in context.  Errors are identified using a specific classification system.  Steps performed without error are used to calculate a percentage mastery score.  Stage two, the Comparative Analysis of Performance – Motor (CAP-M), is used to identify the specific range of motion and motor actions contributing to errors identified in Stage one.  Stage two is based on a comparative method of observation, and employs concepts of positive and negative symptoms.  The symptoms identified through the CAP-M are used to select and apply impairment-focused interventions, and to embed these interventions within task oriented therapy programs.   The validity of the CAP-M has been demonstrated (Rae, Copley & Ranka, 2010).  The ULPA has been used to investigate upper limb task performance and action changes in adults with acquired brain injury pre- and post- injection with Botulinum toxin A.