The concept of formal or standardized tests for assessing function came to the fore in the 1960s. Katz et al. acknowledged the hierarchical nature of activities of daily living (ADL) such as eating, continence, transferring, going to the toilet, dressing and bathing in his ’Index of ADL’ and by 1968 ‘ADL’ was an accepted Index Medicus category. The definition of instrumental activities of daily living (IADL) began in 1969 with the work of Lawton and Brody who presented two scales to assess function which recognized the different degrees of complexity required for performing functional tasks. The first scale, taking life maintenance and activities essential for self-care as the primary level, was called the Physical Self-Maintenance Scale.