Backround. Canadian occupational therapists practice in a variety of clinical settings and use different assessment approaches. To understand best practice, this study explored therapists' knowledge use for infant feeding assessments. This was chosen as one specific area of practice to study knowledge use. Purpose. The purpose of this qualtitative study was to investigate what therapists assess and what procedures they use to carry out their assessments. Method. Semi-structured interviews were conducted with 13 therapists with experience evaluating infant feeding. A constant comparative method of data analysis was used to identify common themes. Results. Three themes emerged: the value of medical information, the importance of doing by observing and the need for an adaptive trial and error approach. Practice Implications. These findings suggest therapists' experiential knowledge shape their best practice. This study informs us about the everyday knowledge used by therapists working with infants on feeding issues and helps us to understand why assessment practices may vary amongst therapists and across clinical settings.