It's been over five years since we first purchased a crib mattress as we prepared for the arrival of our first child. A couple of years later, we moved that mattress to a toddler bed. Before long, it was time to get the crib ready for the 'new baby.' We purchased a second crib-sized mattress. Then, the day I caught an 18-month-old Miss M starting to climb out of the crib, we decided it was time to move Miss M into the toddler bed and Big J got a 'big' bed. Today, Miss M got an upgrade to her own 'big' bed. I swapped the kids' bedrooms around today, we purchased a new mattress and box springs, and tonight I tucked each of my children into their own twin-sized bed. There is no longer a crib-sized mattress in use in our house, for the first time in over 5 1/2 years. Part of me is so, so happy - I have always looked forward to my kids reaching the next milestone and celebrating their development. But there is a part of me that's sad - my babies are not babies any more. Still, how can I not celebrate with them? They were both so excited to have 'new' rooms, and Miss M has been looking forward to putting her big bed together for a few weeks now. Doesn't she look happy?