Howard and Bernadette were engaged in "The Herb Garden Germination" (S4E20).
Bernadette tells Howard that she wants to be married to him before he goes into space. The whole gang heads down to city hall, but are too late for that day and they won't reopen until after Howard leaves for Russia.
The ceremony eventually took place on the roof of Leonard, Sheldon and Penny's building. The only attendees were Howard's mother Debbie Wolowitz, Bernadette's father Mike Rostenkowski and Bernadette's mother Mrs. Rostenkowski (appeared in a brief cameo during the couple's kiss when applauding and zooming out from the roof happened). Each of Howard and Bernadette's friends each gave them their own vows. There was one last bit of friction between Leonard and Penny about Leonard's proposal to Penny during sex which Amy eventually put an end to after Penny started reading out her vows. Sheldon attempted to do his vows in Klingon but Bernadette stopped him since she disallowed him to do that.
At the end, Howard and Bernadette had their first kiss as a married couple and then the camera cut to over their heads, then backed out further showing their friends, Mrs. Wolowitz, Mike and Mrs. Rostenkowski clapping and then of the building then all the way to space with a full view of the Earth. Mrs. Wolowitz was also seen for the first time during the backing out.
- Mrs. Rostenkowski (Bernadette's mother) was not seen with an actual appearance at the wedding, but was seen in her white wedding clothes (with her face not seen, as of it being covered with her cream hat) standing next to Mike (Bernadette's father) when it is captured from space.
- There are some people who Howard and Bernadette both know or separately know, either family and friends who are absent from the wedding, including:
- Joey Rostenkowski
- Bernadette's unnamed siblings
- Bernadette's siblings's spouses
- Bernadette's nephews/nieces
- Leslie Winkle
- Mary Cooper
- Stuart Bloom
- Barry Kripke
- Zack Johnson
- Wil Wheaton
- Eric Gablehauser
- NOTE: Howard's father Sam Wolowitz is gone and Howard's half-brother Josh Wolowitz is not yet known by Howard and Bernadette of his existence, so they aren't there and also Howard's stepmother. Howard would never have invited Leonard's mother Beverly Hofstadter as he hates her and it's unknown why he didn't invite his other family members and why Bernadette's siblings and other family didn't come either.