The RMark package is a collection of R functions that can be used as an interface to MARK for analysis of capture-recapture data. The package contains various functions that import/export capture data, build capture-recapture models, run the FORTRAN program MARK.EXE, and extract and display output. Program MARK has its own user interface; however, model development can be rather tedious and error-prone because the parameter structure and design matrix are created by hand. This interface in R was created to use the formula and design matrix functions in R to ease model development and reduce errors. For more details about its capabilities, download the following RMark documentation archive.