The Institute is an extremely technologically advanced organization, considering the state of the world in Fallout 4. However, many inhabitants of the Commonwealth speak of the Institute in a negative light, almost as an expletive. Whether or not this judgement is warranted will depend on how the player interprets each faction’s motives. Players will in fact be able to join the Institute faction, but not before completing a majority of the main story quests.
The final main quest players encounter in Act II is called “Institutionalized”. In the mission leading up to this quest, players must assemble a device that allows for contact with the organization, calling upon one of the factions for help if desired. Once the device is ready, players will travel to the Institute facility, initiating the Institutionalized quest.
Upon arriving at the facility, enter the elevator and follow the voice that guides you through the area. You will eventually be directed toward meeting the Institute leader, a man who simply goes by Father. After some brief conversation, Father agrees to guide you to Shaun. Afterward, he agrees to personally answer the questions you have regarding the Institute and other matters. Near the end of the conversation, Father offers you the chance to join the Institute. At this point you must oblige in order to complete the quest, but you can revoke your allegiance at a later time.
After speaking with Father, you are allowed to roam about the facility. Use this opportunity to speak with Institute staff, in order to get a feel for the Institute and its motivations. First, locate the Institute Bioscience lab along the main concourse wall and introduce yourself to Dr. Clayton Holdren. Next, track down Chief Engineer Allie Filmore for a brief chat in the main concourse itself. Then, locate and enter the Synth Retention Bureau to speak with Justin Ayo, who seems wary of your intentions. If you have high enough Charisma, you can try to persuade him to trust you through the dialogue options.
Finally, enter the Institute Advanced Systems lab to meet Dr. Madison Li. She will install a device into your Pip-Boy that lets you Fast-Travel to and from the Institute facility. From here you are free to complete Institute faction quests, or continue working with the other factions if you wish. Before leaving the facility, decide whether or not to obtain the Holotape information requested by the other factions by downloading data from the terminal near your Institute landing point.
Keep in mind that working with particular factions will cause you to lose the trust of other factions. Make sure to aid the faction that you truly side with the most or seems to best suit your needs. Your actions within each faction will ultimately impact the conclusion to the main story. Prepare for an intense ending!
Hopefully you are relatively satisfied with whichever ending you receive. For more Fallout 4 features and tips, browse through the various articles in our Fallout 4 Walkthrough and Guide.