When creating development teams, how many members do Scrum guidelines recommend for an optimal team size?

Scrum guidelines suggest that an optimal development team size is between three to nine members. This range is recommended because it strikes a balance between having enough diversity in skills and perspectives to tackle complex problems, while also remaining small enough to maintain effective communication and collaboration. Teams that are too small may struggle to cover all necessary skills and may lack the capability to deliver a potentially shippable Increment. Conversely, teams that are too large can face coordination challenges, difficulties in communication, and reduced individual accountability.

The recommendation of three to nine members ensures that the team is adequately equipped to be self-sufficient, fosters collaboration, and is agile enough to adapt to changes or challenges. Other sizes outside this range, such as having only one member or having ten or more, are not aligned with the principles of Scrum and can hinder the team's performance and effectiveness.