In order to migrate software product variants that are considered similar into a Software Product Line (SPL), it is essential to identify the mandatory and optional features between the product variants. To exploit existing software variants and build a SPL, a feature model of this SPL must be built as a first step. To do so, it is necessary to mine optional and mandatory features from the source code of the software variants. Thus, we propose in this book, a new approach to mine features and feature models from the object-oriented source code of a set of software variants, based on Formal Concept Analysis and Latent Semantic Indexing. To validate our approach, we applied it to ArgoUML and Mobile media case studies. The results of this evaluation validate the relevance and the performance of our proposal as most of the features were correctly identified.