With the rapid advancement of computer and Internet technology and availability of data and information, the need for decision support is continuously growing. In this context, a new vision of Decision Support Systems (DSSs) called situated DSS (SDSS) has been proposed. The key distinguishing features of SDSS include a tight connection with the problem environment, proactive decision supports, and decision implementation. In this work, a layered model of a SDSS is presented. The model includes three layers: the reactive layer, operational layer, and judgmental layer. Since the layered model is structurally different compared to the traditional type of DSS, a new method for designing and development is proposed. The model and method are illustrated through a personal finance management SDSS prototype. The results of the empirical test are presented and discussed.