Located in the south-western suburbs of Melbourne, it includes the south-western hub of Werribee as well as the suburbs of Hoppers Crossing, Tarneit, Truganina, Wyndham Vale and part of Point Cook.

At 9.0%, Lalor has the nation's highest proportion of children aged under 4 years old.

It has the nation's lowest proportion of residents aged 65 and over (7.0%), is sixth highest nationally for families being couples with dependent children (44.4%), and has the sixth highest rate of residents purchasing their own homes (49.3%).

It was named after Peter Lalor, the leader of the miners at the Eureka Stockade, and a former member of the Victorian Legislative Assembly.

It is a safe seat for the Australian Labor Party, which has held it for all except three years of its existence, when it was lost in the 1966 landslide.