diff --git a/books/free-programming-books-langs.md b/books/free-programming-books-langs.md
index 8bc5fcaf8..242b92537 100644
--- a/books/free-programming-books-langs.md
+++ b/books/free-programming-books-langs.md
@@ -2043,6 +2043,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [Functional Programming](https://dcl-prog.stanford.edu) - Sara Altman, Bill Behrman, Hadley Wickham
 * [Introduction to Probability and Statistics Using R](https://github.com/gjkerns/IPSUR) - G. Jay Kerns (PDF)
 * [Learning Statistics with R](https://learningstatisticswithr.com/book/) - Danielle Navarro
+* [Mastering Software Development in R](https://bookdown.org/rdpeng/RProgDA/) - Roger D. Peng, Sean Kross, and Brooke Anderson 
 * [ModernDive](https://ismayc.github.io/moderndiver-book/) - Chester Ismay, Albert Y. Kim
 * [Practical Regression and Anova using R](http://cran.r-project.org/doc/contrib/Faraway-PRA.pdf) - Julian J. Faraway (PDF)
 * [R for Data Science](http://r4ds.had.co.nz) - Garrett Grolemund, Hadley Wickham
@@ -2052,6 +2053,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 * [R Packages](http://r-pkgs.had.co.nz) - Hadley Wickham
 * [R Practicals](http://www.columbia.edu/~cjd11/charles_dimaggio/DIRE/resources/R/practicalsBookNoAns.pdf) (PDF)
 * [R Programming](https://en.wikibooks.org/wiki/R_Programming) - Wikibooks
+* [R Programming for Data Science](https://bookdown.org/rdpeng/rprogdatascience/) - Roger D. Peng 
 * [R Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/rsuccinctly) (PDF, Kindle) (email address *requested*, not required)
 * [Summary and Analysis of Extension Program Evaluation in R](https://rcompanion.org/handbook/index.html) - Salvatore S. Mangiafico
 * [The caret Package](http://topepo.github.io/caret/index.html) - Max Kuhn