The 4400

Australia - M (Recommended for mature audiences.)
M content can only be broadcast between 8:30 p.m. and 5:00 a.m. on any day, and additionally between 12:00 p.m. and 3:00 p.m. on school days.

Germany - 12
Passed only for persons 12 and over.

United States - TV-PG (Parental Guidance Suggested)
This program contains material that parents may find unsuitable for younger children. Many parents may want to watch it with their younger children. The theme itself may call for parental guidance.

United States - TV-14 (Parents Strongly Cautioned)
This program contains some material that many parents would find unsuitable for children under 14 years of age. Parents are strongly urged to exercise greater care in monitoring this program and are cautioned against letting children under the age of 14 watch unattended.

Canada - 14A
Netherlands - 12
New Zealand - M
Singapore - PG

South Korea - 15

The 4400 Episodic Certification

United States - TV-PG

The Wrath of Graham (4x1)
Fear Itself (4x2)
Audrey Parker's Come and Gone (4x3)
The Truth and Nothing But the Truth (4x4)
Try the Pie (4x5)
The Marked (4x6)
Till We Have Built Jerusalem (4x7)
No Exit (4x8)
Daddy's Little Girl (4x9)
One of Us (4x10)

More...

United States - TV-PG-SV

Tiny Machines (4x12)