In this chapter, we introduce the general quantamental approach that we use for nonlinear investing throughout this book. We first discuss the advantages and disadvantages of quantitative and fundamental approaches to investments, then describe the emergence and development of quantamental analysis, and finally demonstrate how to perform quantamental analysis to develop a nonlinear investment strategy. Note that there is a detailed discussion of quantamental methodology in Chapter 9 of my previous book (Ma, L. 2020. Quantitative Investing: From Theory to Industry, pp. 405–451. Berlin: Springer.), some of which, such as basic terms and definitions, is reused here. This book expands on that chapter primarily in terms of quantamental methodology for nonlinear investing in particular, with a focus on applications in real-world investing at different stages of the investment process and across different asset classes.