Kamara, who previously served as associate executive director, steps into a newly created leadership role.
Masterson, who served as the company’s leader from 1981 to 2000, will return to the helm later this summer.
Malgesini will fill the role vacated by former managing director Karen Sharp.
Ross, who’s been with the company since 1992, will depart in 2019.
Tim Richey will bring arts and fundraising experience to the organization.
She will leave the agency in June, at the conclusion of her four-year term.
Maroney will join the theatre following a six-month search.
Hedges will begin the post in Maine next month.
The company’s general manager will step into the role next month.
The co-founder of New York’s Waterwell will take the reins of the Missouri company.