Proximal Causal Learning R package PCL version 1.0 We fit causal models using proxies. We implement two stage proximal least squares estimator. E.J. Tchetgen Tchetgen, A. Ying, Y. Cui, X. Shi, and W. Miao. (2020). An Introduction to Proximal Causal Learning. arXiv e-prints, arXiv-2009 <arXiv:2009.10982>. Software Depends: R (>= 4.0) Andrew Ying <aying9339@gmail.com> Comprehensive R Archive Network (CRAN) Andrew Ying [aut, cre], Yifan Cui [ctb], AmirEmad Ghassami [ctb] GPL (>= 2) 2021-04-10 application/tgz https://CRAN.R-project.org/package=PCL doi:10.32614/CRAN.package.PCL