From helpless newborn to active toddler: It takes just 12 short months for your baby to undergo this incredible transformation. Babies grow and change at an astounding pace, and every month brings new and exciting developments.

New moms and dads often wonder what to expect next and how to know if their baby’s development is on target. Instead of focusing too much on developmental milestones, however, it’s important to remember that babies all develop at their own pace. There’s a fairly wide “window” for when it is normal for a baby to reach a particular developmental stage.

If your baby reaches one milestone sooner, she may reach another one later, because she’s so busy perfecting the other skill. Some babies may say their first word at eight months, while others don’t talk until a little after the one-year mark. And walking may start anytime between nine and 18 months.