Summary Software traceability is the ability to describe and follow the life of a requirement in both a forward and backward direction by defining relationships to related development artifacts. A plethora of different traceability recovery approaches use information retrieval techniques, which depend on the quality of the textual information in requirements and software artifacts. Not only is it important that stakeholders use meaningful names in these artifacts, but also it is crucial that the same names are used to specify the same concepts in different artifacts. Unfortunately, the latter is difficult to enforce and as a result, software traceability approaches are not as efficient and effective as they could be -- to the point where it is questionable whether the anticipated economic and quality benefits were indeed achieved. We propose a novel and automatic approach for expanding corpora with relevant documentation that is obtained using external function call documentation and sets of relevant words, which we implemented in TraceLab. We experimented with three Java applications and we show that using our approach the precision of recovering traceability links was increased by up to 31% in the best case and by approximately 9% on average. The entire code, experimental setup, and results can be obtained from here.                                 Downloads and Experimental Results To reproduce results of our experiments with ENhancing TRAceability usiNg API Calls and rElevant woRds (ENTRANCER), you need to obtain the following components and execute steps. • Subject applications that we used in our experiments can be obtained from here. • The source code for different components of ENTRANCER is available here, • Tracelab components and extensions for ENTRANCER can be downloaded here. • The results of experiments with subject application are available here.   People ENTRANCER was created at the Advanced Research In Software Engineering (ARISE) lab at the Department of Computer Science of the University of Illinois at Chicago where Mark Grechanik leads a research team and Software Engineering Maintenance and Evolution Research Unit at the College of William and Mary headed by Denys Poshyvanyk. Tathagata Dasgupta and Mark Grechanik, Project Leads Emails:tathagatadg[at]gmail.com and drmark[at]uic.edu. Tathagata’s blog is here. Evan Moritz Email: eamoritz[at]email.wm.edu Bogdan Dit Email: bdit[at]email.wm.edu Denys Poshyvanyk Email: denys[at]cs.wm.edu