Understanding the source of voting changes by appellate judges provides an important window into the factors that shape the votes of the judges more generally. We argue that membership changes, by altering the collegial context in which judges make their choices, affect the information environment, long-term collegial considerations, and short-term strategic calculations. As a result, membership change should lead to greater uncertainty and more frequent voting changes among continuing justices in the term following a replacement. We test this proposition by looking at vote change by justices of the U.S. Supreme Court in two separate analyses: justices' votes on search-and-seizure cases since Mapp v. Ohio (1961) and on the progeny of Miranda v. Arizona (1966). Our results support the argument that the collegial context helps explain changes in voting choices. Our analysis suggests that collegial considerations are an important component of judges' behavior and merit further evaluation in a cross-national context.