  I review the observational challenges of finding post T Tauri stars (PTTS),
defined here as low-mass, pre-main-sequence stars with ages of 10^7-10^8 yr.
Such stars are difficult to find because they are less active than younger T
Tauri stars, and they may not be associated with molecular gas. They are useful
for studying the evolution of circumstellar disks and stellar activity between
the 10^6-yr ages of nearby star-forming regions and the main sequence. However,
care must be taken in the search process so that the selection criteria used to
locate such stars do not bias the sample used for subsequent evolutionary
studies.
