A computer system is disclosed which may adopt one of many personas, depending upon the role that its owner is currently playing. The computer system includes a central repository of extensible personas available to all applications running on the computer system. Each such persona has associated therewith a suite of parameters, or specific values for parameters, which are appropriate for conducting computer implemented transactions under a particular persona. The computer system further includes a graphical user interface which allows the user to switch from persona to persona by selecting a particular persona from a list of available personas displayed on a display screen of the computer system. By selecting such persona, the user causes the computer system to globally change the entire suite of parameter values so that subsequent transactions conducted with the computer system employ the parameter values of the current persona.