A system for treating a bifurcated vessel, said system comprising: a first delivery catheter comprising: a first elongate shaft having proximal and distal ends, an expandable member disposed adjacent the distal end of the first elongate shaft, and a first radially expandable stent disposed over the expandable member, the first radially expandable stent having a sidewall with a side hole passing therethrough; and a second delivery catheter comprising: a second elongate shaft having proximal and distal ends, a proximal expandable member and a distal expandable member, and a second radially expandable stent disposed over the distal expandable member, and wherein the first radially expandable stent has a crimped configuration and a radially expanded configuration, and in the crimped configuration the first radially expandable stent is configured for delivery to a treatment site in the bifurcated vessel, and in the radially expanded configuration the first radially expandable stent is configured to support the treatment site, and wherein the first radially expandable stent is crimped to and disposed over the expandable member and a proximal end of the proximal expandable member, and wherein the second elongate shaft passes through the side hole, and wherein radial expansion of the proximal expandable member (5 120) radially expands a proximal portion of the first radially expandable stent thereby allowing movement of the second elongate shaft relative to the first elongate shaft and the first radially expandable stent. a first delivery catheter comprising: a first elongate shaft having proximal and distal ends, an expandable member disposed adjacent the distal end of the first elongate shaft, and a first radially expandable stent disposed over the expandable member, the first radially expandable stent having a sidewall with a side hole passing therethrough; and a first elongate shaft having proximal and distal ends, an expandable member disposed adjacent the distal end of the first elongate shaft, and a first radially expandable stent disposed over the expandable member, the first radially expandable stent having a sidewall with a side hole passing therethrough; and a second delivery catheter comprising: a second elongate shaft having proximal and distal ends, a proximal expandable member and a distal expandable member, and a second radially expandable stent disposed over the distal expandable member, and a second elongate shaft having proximal and distal ends, a proximal expandable member and a distal expandable member, and a second radially expandable stent disposed over the distal expandable member, and wherein the first radially expandable stent has a crimped configuration and a radially expanded configuration, and in the crimped configuration the first radially expandable stent is configured for delivery to a treatment site in the bifurcated vessel, and in the radially expanded configuration the first radially expandable stent is configured to support the treatment site, and wherein the first radially expandable stent is crimped to and disposed over the expandable member and a proximal end of the proximal expandable member, and wherein the second elongate shaft passes through the side hole, and wherein radial expansion of the proximal expandable member (5 120) radially expands a proximal portion of the first radially expandable stent thereby allowing movement of the second elongate shaft relative to the first elongate shaft and the first radially expandable stent. wherein the first radially expandable stent is crimped to and disposed over the expandable member and a proximal end of the proximal expandable member, and wherein the second elongate shaft passes through the side hole, and wherein radial expansion of the proximal expandable member (5 120) radially expands a proximal portion of the first radially expandable stent thereby allowing movement of the second elongate shaft relative to the first elongate shaft and the first radially expandable stent.