Here are some apartments in Delaware County/Main Line that advertise rentals to families with pets:

Glen Brook Apartments
223 South MacDade Boulevard
Glenolden, PA  19036
(610) 586-0300

Glen Manor Apartments
200 Karen Circle
Glenolden, PA 19036
(610) 532-0900

Ridley Brook Apartments
111 MacDade Blvd.
Folsom, PA  19033
(610) 521-4343

Stonewood Village
300 Walnut Street, #603
Ridley Park, PA 19078
(610) 521-2259 Fax (610) 521-2542

 Home Properties of Devon
300 Avon Road
Devon, PA 19333
(610) 687-4522

Home Properties of Bryn Mawr
105 H1 Charles Drive
Bryn Mawr, PA 19010
(610) 525-2088

William Henry Apartments
1086 King Road
Malvern, PA 19355
(610) 644-1155

New Orleans Park
943 South Avenue
Secane, PA 19018
(610) 544-1525

Golf Club Apartments
1100 West Chester Pike
West Chester, PA 19382
(610) 692-4383

Windsor at Windermere Place
1500 Windermere Road
West Chester, Pa 19380
610-692-3060
http://www.windsorcommunities.com/windermere

http://www.petcaregroup.com/everyone/localresources.asp

MyApartmentMap-a great tool for finding pet-friendly housing all over the USA!