For U.S. research universities, cluster hiring has become a popular means to add faculty members in university-defined priority fields. The expectation of advocates is that these faculty members will collaborate on high-impact research. Utilizing a national sample of 168 cluster-hire faculty members from eight U.S. research universities, we find statistically significant gains in research output, collaborations, and research impact from pre- to post-hire. However, these gains are not distributed equally. Some output and impact measures show greater gains for white and Asian researchers relative to under-represented minorities and for men relative to women. Significant gains in research output are associated with fields like advanced materials and health sciences for which generous external support is available. Significant research impact is associated with researchers located in wealthy, prestigious universities. The findings indicate that cluster hiring is no cure-all for fields that are disadvantaged in the competition for external funding or for non-elite universities that are disadvantaged in the competition for prestige.