An Acceptance Test Driven Development (ATDD) developer helps to streamline the software development process by defining acceptance criteria before coding commences. They write acceptance tests based on user expectations, which ensures that the software developed meets the user's needs and expectations. They collaborate with stakeholders, including other developers, testers, and business representatives, to ensure that everyone understands the software requirements. The ATDD developer's work promotes communication, reduces misunderstandings, and helps to deliver high-quality software. They also contribute to refining the software by performing regular tests and feedback loops.