A surgical system comprising: a surgical instrument comprising an elongate shaft with proximal and distal ends, an end effector on the distal end and a mounting means laterally extending from the shaft intermediate the proximal and distal ends, the instrument further comprising actuating means for actuating the end effector; an instrument base supported by a remote center device; an instrument holder means for releasably holding and supporting the instrument, the instrument holder means comprising an actuator driver for releasably holding and moving the actuator means of the surgical instrument, the instrument holder means releasably mounted to the instrument base; and a remote center device for constraining movement of said instrument about a desired spherical center of rotation at a desired location along said instrument, the remote center device comprising: a base plate; a first linkage means pivotally mounted on said base plate for rotation about an axis, said instrument holder means being configured to hold said instrument in a position so that the desired remote center of spherical rotation along the instrument intersects said axis; and a second linkage means connected to said instrument holder means for moving said instrument holder means in a parallel-plane relationship to said second linkage means, said second linkage means being pivotally connected to said first linkage means so that said second linkage means remains parallel to said axis and said first linkage means remains parallel to the instrument; wherein said first and second linkage means (321, 323) are configured to constrain movement of said instrument, such that said desired location on said instrument remains fixed at said spherical center of rotation. a surgical instrument comprising an elongate shaft with proximal and distal ends, an end effector on the distal end and a mounting means laterally extending from the shaft intermediate the proximal and distal ends, the instrument further comprising actuating means for actuating the end effector; an instrument base supported by a remote center device; an instrument holder means for releasably holding and supporting the instrument, the instrument holder means comprising an actuator driver for releasably holding and moving the actuator means of the surgical instrument, the instrument holder means releasably mounted to the instrument base; and a remote center device for constraining movement of said instrument about a desired spherical center of rotation at a desired location along said instrument, the remote center device comprising: a base plate; a first linkage means pivotally mounted on said base plate for rotation about an axis, said instrument holder means being configured to hold said instrument in a position so that the desired remote center of spherical rotation along the instrument intersects said axis; and a second linkage means connected to said instrument holder means for moving said instrument holder means in a parallel-plane relationship to said second linkage means, said second linkage means being pivotally connected to said first linkage means so that said second linkage means remains parallel to said axis and said first linkage means remains parallel to the instrument; wherein said first and second linkage means (321, 323) are configured to constrain movement of said instrument, such that said desired location on said instrument remains fixed at said spherical center of rotation. a base plate; a first linkage means pivotally mounted on said base plate for rotation about an axis, said instrument holder means being configured to hold said instrument in a position so that the desired remote center of spherical rotation along the instrument intersects said axis; and a second linkage means connected to said instrument holder means for moving said instrument holder means in a parallel-plane relationship to said second linkage means, said second linkage means being pivotally connected to said first linkage means so that said second linkage means remains parallel to said axis and said first linkage means remains parallel to the instrument; wherein said first and second linkage means (321, 323) are configured to constrain movement of said instrument, such that said desired location on said instrument remains fixed at said spherical center of rotation.