One of the core roles of a practising geotechnical engineer is to analyse and design foundations. This textbook for advanced undergraduates and graduate students covers the analysis, design and construction of shallow and deep foundations and retaining structures as well as the stability analysis and mitigation of slopes. It progressively introduces critical state soil mechanics and plasticity theories such as plastic limit analysis and cavity expansion theories before leading into the theories of foundation, lateral earth pressure and slope stability analysis. On the engineering side, the book introduces construction and testing methods used in current practice. Throughout it emphasizes the connection between theory and practice. It prepares readers for the more sophisticated non-linear elastic-plastic analysis in foundation engineering which is commonly used in engineering practice, and serves too as a reference book for practising engineers. A companion website provides a series of Excel spreadsheet programs to cover all examples included in the book, and PowerPoint lecture slides and a solutions manual for lecturers. Using Excel, the relationships between the input parameters and the design and analysis results can be seen. Numerical values of complex equations can be calculated quickly. non-linearity and optimization can be brought in more easily to employ functioned numerical methods. And sophisticated methods can be seen in practice, such as p-y curve for laterally loaded piles and flexible retaining structures, and methods of slices for slope stability analysis.