This paper presents a design space for intelligent and interactive writing assistants, aiming to provide a structured way to explore the multidimensional space of these systems. The design space is based on five key aspects: task, user, technology, interaction, and ecosystem. These aspects are interconnected and interdependent, and each includes dimensions and codes that represent fundamental components and potential options for each dimension. The design space was developed through a systematic literature review of 115 papers, with an iterative coding process involving multiple teams. The result is a comprehensive framework that includes 35 dimensions and 143 codes, covering a wide range of writing contexts, user relationships, and ecosystem considerations. The design space aims to provide researchers and designers with a practical tool to navigate, understand, and compare the various possibilities of writing assistants, and to aid in the envisioning and design of new writing assistants. The paper also discusses the challenges and considerations in the development of writing assistants, including the need for a holistic view of the sociotechnical systems and the ethical implications of their use. The design space is publicly released as a living artifact to encourage community involvement in refining and extending the design space.This paper presents a design space for intelligent and interactive writing assistants, aiming to provide a structured way to explore the multidimensional space of these systems. The design space is based on five key aspects: task, user, technology, interaction, and ecosystem. These aspects are interconnected and interdependent, and each includes dimensions and codes that represent fundamental components and potential options for each dimension. The design space was developed through a systematic literature review of 115 papers, with an iterative coding process involving multiple teams. The result is a comprehensive framework that includes 35 dimensions and 143 codes, covering a wide range of writing contexts, user relationships, and ecosystem considerations. The design space aims to provide researchers and designers with a practical tool to navigate, understand, and compare the various possibilities of writing assistants, and to aid in the envisioning and design of new writing assistants. The paper also discusses the challenges and considerations in the development of writing assistants, including the need for a holistic view of the sociotechnical systems and the ethical implications of their use. The design space is publicly released as a living artifact to encourage community involvement in refining and extending the design space.