Eli Whitney revolutionized the manufacturing of rifles using interchangeable parts. Henry Ford did the same for automobiles, integrating the idea of interchangeable parts and an assembly line. A growing number of software development organizations are adopting approaches that emphasize proactive reuse, interchangeable components, and multiproduct planning cycles to construct high-quality products faster and cheaper. Standard methods, referred to as software product line or software family practices, have developed around these approaches. This special issue focuses on the technical, managerial, and organizational activities related to introducing these practices. Introducing product line practices into an organization typically involves many levels of the enterprise. Organizations have employed two main types of strategies when introducing software product lines: heavyweight and lightweight. With heavyweight strategies, a product line’s initial product costs significantly more than an initial product in single-system development (see Figure 1). However, after approximately three products, the product line has lower cumulative costs. In contrast, lightweight strategies require minimal upfront investment. The initial cost falls somewhere between the single-product cost and heavyweight cost (see Figure 1). The tradeoff for lower upfront costs is that it takes longer to reduce cumulative costs.