All of the great Catholic religious orders have their associated laypeople. Franciscans have their Secular Order, Carmelites their Third Order, Dominicans have their Tertiaries, Benedictines have their Oblates, Passionists have their Associates, and so forth; and the differences are very slight. Third (or Secular) Orders are literally “third” parts of the Dominican, Franciscan and Carmelite families and those laypeople who join them try to adapt the charisms and characteristics of each order into their daily routines, which in turn tends to shape their lives in ways reflective of the lives of their vowed brothers and sisters.
I'm posting it for a few reasons: I learned new things, I think our dear readers would be interested, and I know Francesca would be interested. (So here you go, dear!)
On a related note, happy feast day to all you Roses. It's easy to think Saint Rose of Lima was a professed nun since she's typically pictured in full religious garb, but out of obedience to her parents she instead became a Dominican tertiary.
Thank you to the Anchoress, herself a Benedictine Oblate.
Image credit: SQPN