The Catholic Education Resource Center has posted an article that originally appeared in the June 1995 issue of Homiletic & Pastoral Review concerning the wearing (or not wearing, as the case may be) of clerical clothing by priests. After quoting the relevant sections of the 1994 Directory for the Ministry and Life of Priests, the authors (a monsignor and a priest) give 23 reasons why a priest should wear his collar. They then provide and rebut 14 common arguments against wearing the collar.
To priests who always wear the Roman collar we say: keep it up! To those who do not we say: take stock of the value which this seemingly insignificant piece of vesture possesses. Be aware that the priestly work you now do will not suffer but will be enhanced when you dress according to the venerable custom of the Church.
(H/T: Rich Leonardi)