Challenge Rating vs Level Adjustment [PF]

[Retech]

What is the relationship between the boost to challenge rating and the level adjustment of a template? Is there some sort of general rule (or even better, a specific rule) for it?

While this is Pathfinder, I suspect that it is the same in 3.5. I'm interested in being a half dragon:

http://www.d20pfsrd.com/bestiary/monster-listings/templates/half-dragon

But there is no level adjustment listed. Is there a listing for half-dragon template in the one of the 3.5 books?

[Starbuck_II]

What is the relationship between the boost to challenge rating and the level adjustment of a template? Is there some sort of general rule (or even better, a specific rule) for it?

While this is Pathfinder, I suspect that it is the same in 3.5. I'm interested in being a half dragon:

http://www.d20pfsrd.com/bestiary/monster-listings/templates/half-dragon

But there is no level adjustment listed. Is there a listing for half-dragon template in the one of the 3.5 books?

Pathfinder uses CR as Level adjustment. This is basis for playing monsters as characters.
http://paizo.com/pathfinderRPG/prd/monsters/monstersAsPCs.html