From Center City: 

If you are headed to a sporting event or concert, the Broad Street Line (aka the Subway or the Orange Line) is a fast, easy and cheap way to get from Center City to the Stadium Complex (Citizens Bank Park, Lincoln Financial Field, and the Wachovia Center).  You can enter the Subway at Broad & Locust St, near the Doubletree Hotel.  Take the Broad Street line southbound to AT&T Station (Formerly Pattison Station) - the last stop.  Purchase tokens for your trip ($1.80 each in packs of two, five, or ten) before you ride; it'll save nearly $1 over the cash fare. It's a good idea to buy your tokens for the return trip in advance.  If you are using a pass, then you won't need tokens.

For more details on public transportation in Philadelphia , see Public Transportation

From 30th Street Station:

Purchase two tokens for your trip. This can be done in the ticket booth in the SEPTA area at 30th Street Station (ask at the information desk in the center of the station if you can't find the SEPTA area).

Leave the station on the 30th Street side. Cross 30th Street, and you will see a portal for the Market-Frankford subway line (Blue Line). Go down the steps, pay your fare with one token, and take the Market-Frankford line eastbound (towards Frankford Terminal) to 15th Street (one stop). When you get off the train, walk to the left to the end of the platform. Follow the signs for the Broad Street Subway (Orange Line). Take the Broad Street Subway southbound to the last stop, AT&T Station. Follow the crowd to the venue. Be sure to stay within the areas marked "Free Interchange" in order to avoid paying a second fare.

For the return trip, you will make your way back to the AT&T station, but you will not have to wait in the longest line (cash fares) because you have the token.  Any line that is moving quickly will do. Take whichever train is leaving next to the City Hall station. When you exit the train, follow the signs for the Market-Frankford Line westbound (towards 69th Street). Take the Market-Frankford line one stop to 30th Street.

Depending on waitng times for each train, the trip should take somewhere between 25 to 45 minutes.

For more details on public transportation in Philadelphia , see Public Transportation

From New Jersey: 

There are a several options to get from NJ to the Philadelphia Sports Complex.

Option #1. The speedline to 12/13th and Locust or 15/16th and Locust, change there for the Broad Street Subway (see From Center City, above). To get back from the game take the Broad st line to Walnut/Locust, and follow the signs for PATCO. (Note that Walnut/Locust connects to both the 15/16th and 12/13th, however 15/16th is accessible while 12/13th is not).

Option #2. Bus. Taking a New Jersey Transit bus to the game? Take the bus to Philly get off the bus at City Hall and take the Broad St. Line south to Pattison.

To go home to NJ, take the subway to either City Hall or Race/Vine as the NJT stop on Broad heading toward NJ is right above the station. (note that bus routes in the 3 and 5 hundreds originate and terminate at the Greyhound terminal.)

Option #3. the Atlantic City line. NJT's Atlantic City line runs from A.C to Philly going through the Pine Barrons. Take NJT to 30th then at 30th take the Market Frankford Line subway or a Trolley to 15th, change there for the Orange line South.

Option 4. The Riverline. Take the River Line to Walter Rand Transit Center in Camden, Change there for either the Bus or Speedline to Philly and follow the Respective Directions from there. (Note the Riverline stops running to Trenton at 9:30p.m, however runs until midnight to Pennsauken/R.t 73 station).

Option #5. New Jersey Transit/SEPTA Regional Rail Line combo. This is for people coming above Trenton. Take the Northeast corridor to Trenton. Change in Trenton to the SEPTA Regional Rail Line (Formerly R7), and take it to Suburban Station. Change there for the Broad Street (Orange) Line. It's a long walk- just follow the signs.