The Sims 2 Guide and FAQ

1.4.1 Aspiration Points
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Each time your Sim achieves one of there aspiration wants there are given 
aspiration points. These points can then be used to 'purchase' aspiration 
rewards. See section 9.1 for a list of the Aspiration rewards.

The amount of aspiration points earned for a want are relative to the value of
the want towards the Sims aspiration. However some wants will always be the same
for all Sims regardless of the Sims Aspiration. An example of this is 'Get 
SimChildName into Private School'. 

You can also loose your Aspiration Points by fulfilling your Sims fears. Fears 
can take a number forms and be aspiration related and non aspiration related.