I'm retired Air Force and now a Civil Service employee with 6 years down and ?????? to go. I figure, if the economy improves and the taxes don't kill us I have about 18 years left till retirement. I've been reading the posts on the website and really like the information I am gaining about TSPs. I do have a question. I noticed the S fund is doing the best percentage wise but it is also the most expensive per share. Which is the best option, to go with what is performing the best (S fund), or what is the cheapest to buy (C or I fund)? Thanks, and I really appreciate the insight given on this site.