<p>Do you mean summer classes in a subject of choice in your country, or attending summer school at a college in the US? Summer classes in your country MIGHT help indirectly, but summer school at a college in the US will not help directly with admissions. For instance, attending Harvard summer school will not help you get into Harvard. It may help in increasing fluency but any American college program will help with that and you’ll have no advantage at that specific college compared to students who didn’t attend the summer program at that college. In addition, these classes MUST be “non credit” or HS level, not college-level.</p>
<p>Your friend needs to check the college websites for all schools he is interested in and see what their policies are for applying as a fr vs. transfer applicant. At some schools, taking as little as 1-post HS college class (anywhere as all transcripts must be submitted) will mean he has to apply as a transfer, which can have an impact on admission, need based FA and merit awards.</p>