The tecla library provides UNIX and LINUX programs with interactive command line editing facilities, similar to those of the unix tcsh shell. In addition to simple command-line editing, it supports recall of previously entered command lines, TAB completion of file names or other tokens, and in-line wild-card expansion of filenames. The internal functions which perform file-name completion and wild-card expansion are also available externally for optional use by programs, along with a module for tab-completion and lookup of filenames in a list of directories. Note that special care has been taken to allow the use of this library in threaded programs. The option to enable this is discussed in the Makefile, and specific discussions of thread safety are presented in the included man pages. WWW: http://www.astro.caltech.edu/~mcs/tecla/