Lizzy Caplan wants to marry boyfriend Tom Riley.

The 34-year-old American actress - who is currently dating the English actor, with who she lives in North East London for six months of the year with - has admitted she ''would'' like to get married and have a ''big family'' in the future.

Speaking to You magazine about her future plans to settle down, the brunette beauty said: ''I would [like to get married]. I'm a bit old-fashioned that way. I can see why in this day and age a lot of marriages end in divorce, but I think there's no more romantic a notion than swinging the bat and saying, 'It's going to be different for me.' It does take guts and a lot of work, but even if you fail. I think there's something noble in the attempt. I was lucky in that my parents have been married for 25 years and it was a healthy relationship.

''[I have] always wanted a big family, but I don't know how realistic that would be.''

And the 'Masters of Sex' star has revealed she would love to mother four children, but thinks she is getting ''too old'' to make that happen.

She explained: ''If I could have four kids, I would be very happy, but I'm getting a little old for four now.

''That said, I have a new puppy and I put a lot of maternal energy into that poo dog, so for now, I'm good.''

Meanwhile, the brunette beauty has admitted she seeks relationship advice from those who are in long-term relationships.

She said: ''Whenever I meet anybody in a long-term relationship, I ask them what their secret is. It seems to be: just genuinely like the other person, because all the other stuff ebbs and flows.''