Traditional product development efforts are primarily based on well-structured and hierarchical product development processes. The products are systematically decomposed into subsystems that are designed by dedicated teams with well-defined information flows. Over the last 2 decades, a new product development approach called mass-collaborative product development (MCPD) has emerged. The fundamental difference between a traditional product development process and a MCPD process is that the former is based on top-down decomposition while the latter is based on evolution and self-organization. The paradigm of MCPD has resulted in highly successful products such as Wikipedia, Linux, and Apache. Despite the success of various projects using MCPD, it is not well understood how the product architecture affects the evolution of products developed using such processes. Toward addressing this gap, we present an agent-based model to study the effect of product architectures in MCPD processes. The model is executed for different architectures ranging from slot architecture to bus architecture and the rates of product evolution are determined. The agent-based modeling approach allows us to study how (a) the degree of modularity of products and (b) the sequence of decoupling affect the evolution time of individual modules and overall products developed through MCPD processes. The approach is presented using the architecture of mobile phones as an illustrative example. This approach provides a simple and intuitive way to study the effects of product architecture on the MCPD processes. It is helpful in determining suitable strategies for product decomposition and module decoupling, and in identifying the product architectures that are suitable for MCPD processes.