Context: Since software development is a complex socio-technical activity that involves coordinating different disciplines and skill sets, it provides ample opportunities for waste to emerge. Waste is any activity that produces no value for the customer or user. Objective: The purpose of this paper is to identify and describe different types of waste in software development. Method: Following Constructivist Grounded Theory, we conducted a two-year five-month participant-observation study of eight software development projects at Pivotal, a software development consultancy. We also interviewed 33 software engineers, interaction designers, and product managers, and analyzed one year of retrospection topics. We iterated between analysis and theoretical sampling until achieving theoretical saturation. Results: This paper introduces the first empirical waste taxonomy. It identifies nine wastes and explores their causes, underlying tensions, and overall relationship to the waste taxonomy found in Lean Software Development. Limitations: Grounded Theory does not support statistical generalization. While the proposed taxonomy appears widely applicable, organizations with different software development cultures may experience different waste types. Conclusion: Software development projects manifest nine types of waste: building the wrong feature or product, mismanaging the backlog, rework, unnecessarily complex solutions, extraneous cognitive load, psychological distress, waiting/multitasking, knowledge loss, and ineffective communication.