These pants are such great quality! perfectly match the jacket and we loved being able to mix and match sizes. The waist is SUPER adjustable but the length was PERFECT and we ended up putting the waist down to almost the smallest size - the waist is adjusted with a button and elastic tab which is PERFECT for a growing little kiddo. unlined. nice crease in front - just like a "grown up" pant suit. my son just turned 5 year old a couple weeks before and he is slightly petite and very slender and the size 5 for pants and jacket were perfect (he is about 42" tall and 40 lbs). We purchased the matching jacket as well (in the same size - 5). Highly recommended these are comfortable, quality fabric - no polyestery swish swoosh here! A+++