This paper provides an introduction to the geotechnical design of suction caisson foundations for Offshore Wind Turbine (OWT) foundations. It summarizes the experience gained in a number of projects from across the world and proposes a guidance for the design of future projects. The paper is structured in a logical manner; the first section introduces the general design approach of suction caisson foundations, whereas the individual design aspects are discussed in detail in the subsequent sections. Therein, all relevant aspects are covered, including design basis, installation-, capacity- and serviceability-analysis, assessment of the foundation stiffness, and soil reactions. In the last section other aspects such a grouting, integrated analysis, and application of the presented approach to complete wind farms is briefly discussed.