There are many different conceptual definitions of frailty in circulation. Most of these definitions focus mainly on physical problems affecting older people. Only a few also draw attention to other domains of human functioning such as the psychological domain. The authors of this article fear that this could lead to fragmentation of care for frail older people. The aim is to develop an integral conceptual definition of frailty that starts from the premise of a holistic view of the person.To achieve this, a literature search was carried out. Thereafter a group of experts (N=20) were consulted, both verbally during 2 expert meetings and via a written questionnaire. These experts were asked which existing conceptual definition of frailty places most stress on the integral functioning of older people.The experts expressed a clear preference for one of the conceptual definitions. The result of the literature search and the consultation with the experts led to a new integral conceptual definition of frailty.The conceptual definition is intended to offer a framework for an operational definition of frailty for identifying frail older people.