This study is an in-depth exploration of the growth and development processes of circular new ventures. A unique data set followed 70 such ventures longitudinally between 2021 and 2023. One observation is that new ventures tend to take an experimental approach when developing their circular business models to address the real needs of potential customers and capture value based on circularity. Another is that, from their inception, these ventures have an active interest in becoming part of a business ecosystem. Challenges of circular new ventures related to their liabilities of newness include their limited resources, lack of networks and legitimacy which makes it difficult for such ventures to secure strategic partnerships. Thus, contrary to expectations of rapid scale-up, circular new ventures often must partner with and grow slowly with other small and new ventures.