Converting a mountain bike to a street bike

[Water Hazard]

Does anyone know of any complications/issues that might arise from converting an entry level mountain bike into a street bike? I'd like to put some thinner tires on my mountain bike in order to be able to participate in a longer road ride.

What types of problems would I possibly run into?

Thanks!

[30 inch eyes]

I did this on one of my bikes. didn't have any problems. it's still a mountain bike though, meaning it's not the same gearing as a road bike, but you should get some more speed out if it, because of the less aggressive tire tread.

[ChemE]

I had to swap the suspension fork for a solid fork. The stiffer front end makes for better energy transfer to the rear wheel. This can be a bit tricky with newer bikes with larger diameter head tubes.