Dramatic changes occur during this part of the first year of life, as your baby's physical and intellectual abilities take an immense leap forward. Your 6- to 9-month-old will probably learn to sit, stand, and perhaps even crawl. In this period, babies also begin to perform deliberate actions that demonstrate their ability to remember and think. This will undoubtedly take your interactions and play with them to a whole new, even more rewarding, level.
MILESTONES
As you eagerly anticipate your baby's new mobility and achievements, remember that milestones only represent the average age that the average baby accomplishes any given task. As we're sure you're already aware, your child is a unique individual who is likely to be anything but average! Some milestones may be reached early, while he make take his own sweet time mastering others. If you have any concerns about your baby's progress, however, don't hesitate to discuss them with your baby's doctor.
In general, infants between 6 and 9 months old: Sit unassisted. While many infants start to work on their sitting skills before this age, their ability to sit well (in other words, without tipping over and hurting themselves) takes some time. By 7 months, the average infant can sit while leaning on both hands for support. By a month later, he will progress to sitting alone without support, and by 9 months, most can reliably sit unassisted for longer periods of time.
Start to stand. The timing of this milestone tends to vary greatly from one infant to the next. That said, many infants between 6 and 9 months will begin to bear weight on their feet and legs, and by 9 months or so, may even be able to pull to a stand while holding onto furniture.
Consider crawling. The reason we say "consider" is because while infants are generally capable of pulling themselves along with their arms (some even getting up on their hands and knees) by around 9 months of age, the fact is that there are some infants who never crawl. And while the parents of those infants often are greatly concerned, crawling is not truly a milestone, but rather, it is but one way of assessing whether a child's muscle strength and motor development are developing. If you are concerned about your own baby's lack of interest, discuss it with his pediatrician before spending much time worrying about it!
Babble. During these months, most babies start to vocalize a lot more in ways other than crying, not the least of which is laughing more frequently. You're also likely to notice a progression in your baby's talking abilities — from making four different consonant sounds or stringing together chains of vowel-consonant sounds to combining syllables into word-like utterances and shouting to attract attention.
Develop better control of their actions. Babies this age not only start to imitate actions and intentionally reach for toys placed just out of reach, but they also become more skilled at transferring objects from hand to hand — not to mention banging them on a table! While it may take a couple of months before your baby can easily pick up small objects between his thumb and first finger (known as a pincer grasp), you will probably see your child starting to try.
Aren't fooled by out of sight, out of mind. Six- to 9-month-olds are busy developing a better awareness of the world around them. This includes an ability to understand that objects still exist, even though they are not in sight, a concept known as "object permanence." You may notice examples of this as your 7-month-old starts to look briefly for toys that have "disappeared," instead of just forgetting about them. By around 8 months, he may even purposely drop things to watch where they go, and actually search for toys after seeing them hidden.
May develop stranger anxiety. Along with an increased awareness of their surroundings, some infants this age also develop what is commonly referred to as stranger anxiety. While some 6- to 9-month-olds start showing increased fear of strangers and distress when their parents leave the room, others may not react this way until well after their first birthday. While such reactions are embarrassing to some parents, you should instead consider your baby's actions to be a normal and healthy
— albeit frustrating — part of growing up.