%0 Journal Article %T Power %A Saurabh Pant %J Journal of Theoretical Politics %@ 1460-3667 %D 2018 %R 10.1177/0951629817729225 %X Power-sharing arrangements between a leader and a popular outsider can be mutually beneficial and threatening. The literature has focused primarily on the former¡¯s trade-off where a leader gains legitimacy when sharing power with a respected outsider but also subsequently creates a rival who could challenge their rule. Yet this outsider also faces a simultaneous trade-off between power and credibility in acquiescing to the leadership. I incorporate both coinciding trade-offs in developing a formal model to examine such power-sharing arrangements which have been prevalent historically and currently. I illustrate a ¡®discontinuity¡¯ in optimal power sharing where a leader either shares nothing or shares a specific amount to compensate the rival for the rival¡¯s lost credibility. Counterintuitively, I further show that the leader should share more power with less trustworthy rivals to reduce their strong incentives to challenge. I then revisit the Investiture Controversy in medieval Europe using these insights from the model %K Formal models %K legitimacy %K political survival %K power sharing %U https://journals.sagepub.com/doi/full/10.1177/0951629817729225