Why do good teams fail? Very often, argue Deborah Ancona and Henrik Bresman, it is because they are looking inward instead of outward. Based on years of research examining teams across many industries, Ancona and Bresman show that traditional team models are falling short, and that what's needed--and what works--is a new brand of team that emphasizes external outreach to stakeholders, extensive ties, expandable tiers, and flexible membership. The authors highlight that X-teams not only are able to adapt in ways that traditional teams aren't, but that they actually improve an organization's abi.