Example 1: A British student who lost her memory because of a severe brain disease has earned a degree in psychology. Example 2: 'My mum would drive me to lectures and sit outside in the car because I was finding small things like finding my way around and understanding directions difficult.' 'Because' is a very common word. It states the reason for something. For example, 'I want to see Collateral because I like Tom Cruise a lot.' Take a look at Examples 1 and 2: both use the word 'because', however, one is followed by 'of' while the other is not. We use 'because of' when the reason that follows is a noun or noun phrase. In Example 1, the reason - a severe brain disease - is a noun phrase. When the reason that follows 'because' is a complete sentence, we simply use 'because', without 'of'. In Example 2, the reason is a complete sentence: 'I was finding small things like finding my way around and understanding directions difficult.'