A method for avoiding undesirable overshoot and undershoot of a temperature band bounding a control temperature set point for a temperature within a temperature controlled space, including the steps of selectively operating a transcritical refrigerant vapor compression system for supplying conditioned air to a temperature controlled space in at least one higher capacity mode or in at least one lower capacity mode; and operating the transcritical refrigerant vapor compression system in at least one transition mode when staging up or staging down between the higher capacity mode and the lower capacity mode characterized in that operation in the transition mode comprises: monitoring a temperature control differential (TSETPT - TCRTL), between a control temperature set point (TSETPT), and a sensed control temperature (TCRTL); and establishing a trend in a change of the temperature control differential over an elapsed time, wherein establishing a trend in a change of the temperature control differential over an elapsed time comprises calculating an average derivative of the temperature control differential over the elapsed time, and entering a stage down transition mode when staging down from operation in a high capacity mode to operation in one of a first low capacity mode and a second lower capacity mode; determining whether the average derivative of the temperature control differential has been positive for an elapsed time greater than a preset first period of time; and if the average derivative of the temperature control differential has been positive for an elapsed time greater than the preset first period of time, staging down to the second lower capacity mode bypassing the first low capacity mode. selectively operating a transcritical refrigerant vapor compression system for supplying conditioned air to a temperature controlled space in at least one higher capacity mode or in at least one lower capacity mode; and operating the transcritical refrigerant vapor compression system in at least one transition mode when staging up or staging down between the higher capacity mode and the lower capacity mode characterized in that operation in the transition mode comprises: monitoring a temperature control differential (TSETPT - TCRTL), between a control temperature set point (TSETPT), and a sensed control temperature (TCRTL); and establishing a trend in a change of the temperature control differential over an elapsed time, wherein establishing a trend in a change of the temperature control differential over an elapsed time comprises calculating an average derivative of the temperature control differential over the elapsed time, and entering a stage down transition mode when staging down from operation in a high capacity mode to operation in one of a first low capacity mode and a second lower capacity mode; determining whether the average derivative of the temperature control differential has been positive for an elapsed time greater than a preset first period of time; and if the average derivative of the temperature control differential has been positive for an elapsed time greater than the preset first period of time, staging down to the second lower capacity mode bypassing the first low capacity mode. monitoring a temperature control differential (TSETPT - TCRTL), between a control temperature set point (TSETPT), and a sensed control temperature (TCRTL); and establishing a trend in a change of the temperature control differential over an elapsed time, wherein establishing a trend in a change of the temperature control differential over an elapsed time comprises calculating an average derivative of the temperature control differential over the elapsed time, and entering a stage down transition mode when staging down from operation in a high capacity mode to operation in one of a first low capacity mode and a second lower capacity mode; determining whether the average derivative of the temperature control differential has been positive for an elapsed time greater than a preset first period of time; and if the average derivative of the temperature control differential has been positive for an elapsed time greater than the preset first period of time, staging down to the second lower capacity mode bypassing the first low capacity mode.