It is of great importance to investigate the characteristics of end-bearing capacity and to determine the resistance factor for rock-socketed piles. In this study, based on the results of 165 compression load tests several key issues with regard to the end-bearing capacity behavior of rock-socket piles were examined. These load tests were conducted on different rocks with different rock-socketed pile conditions throughout the world. The influential factors include the type and the uniaxial natural compressive strength of rocks, the diameter and the embedment depth of socketed piles, and the ultimate end-bearing resistances. In this study, the ratio of ultimate end-bearing capacity to the unconfined compressive strength of the rock was defined as the end-bearing resistance factor of rock-socketed pile. Effects of the key factors on the ultimate end-bearing capacity and the end-bearing resistance factor were comprehensively investigated. An empirical equation between the unconfined compressive strength.