Architects perform problem-solving tasks while designing through various externalization modes. Among the architectural community sketching is associated with conceptual design, and parametric modeling is seen as a tool for detailed design development. However, parametric modeling is increasingly being used for exploring design concepts. We propose that sketching and parametric modeling can be integrated strategically as alternate externalization modes to support problem solving in conceptual design. With sketching, architects are able to externalize their ideas quickly and effortlessly, as the fl exible structure of sketching provokes multiple interpretations through continuous refl ection. With parametric modeling, architects must defi ne a set of parameters and rule-based constraints. By modeling design objects as parametric, multiple design variations can be generated, modifi ed, and evaluated. In this paper we describe an effi cient process of problem-solving by studying the strategic use of sketching and parametric modeling in conceptual design. We conduct an experiment to explore the processes involved in both modes. Digital sketching is recorded by the Logitech io2 personal digital pen, and parametric modeling using Digital Project software is recorded by screen video capturing software, followed by a retrospective analysis. The ACADIA 2007 competition brief is used as the design task.