Summarize the following:
Be respectful and courteous when you bring it up again. "Have you had any time to think about my Instagram account?" is a great way to broach the subject without coming outright and asking. Allow this to be a conversation, not an argument, but still come ready to explain the site and the measures you'll take to stay safe. Some parents have viable concerns about Instagram, but you can never convince them to let you on if you don't know what is holding them back. Avoid getting angry or picking a fight with them. Listen to their concerns with an open mind -- starting an argument now will only make them less likely to let you online the next time you ask. Common issues with Instagram include:  You aren't mature enough yet. There are bad people on the internet. Public photos will follow you for the rest of your life. This can be one of the most persuasive arguments you have because it shows you know how to be responsible online. It also addresses their concerns before they have a chance to talk about them. Tell them that you are aware of cyberbullying and internet scamming and assure them that you know that photos can last online for a long time. However, you should focus on what you are doing to prevent problems:  Private accounts allow you to manually choose who you let follow you. Anyone can anonymously flag rude, offensive, or explicit content for removal. You do not need to give your real name or contact information on Instagram.  Geotagging, which attaches your location to your photos, can be turned off in "Settings." Let your parents see that you are mature enough to handle the responsibility of an Instagram account. This includes doing your chores and homework on time, listening to their requests, treating your siblings with respect every day. Remember, however, that if you are only doing this to "trick" them into letting you on Instagram you'll likely lose your account the minute you stop being responsible. To get their blessing you need to be respectful every day Private accounts have a lot of benefits that keep you off of search engines and let you control who sees your photos. This is often enough to convince your parents that Instagram is a safe place for you online. As opposed to public accounts, private accounts:  Allow you to accept or deny any new followers. Removes you from search engine results. Hides your information and photos from anyone you have not cleared already. This assures your parents that there is nothing lewd or explicit going on behind their backs. While it may feel weird to "share" your account with your parents, this is a great way to compromise if they still won't let you on. Set up your account together, which lets them see the app first-hand.

Summary:
Ask your parents again 1-2 weeks after the first no. Ask your parents why they are concerned about Instagram. Let them know that you understand internet dangers and how to avoid them. Show your responsibility around the house. Promise that you'll keep your account private. Offer to share your password with your parents, as long as they agree not to post anything.