When Reform won the 1911 election, Massey became Prime Minister and Allen was elevated to Cabinet.
His primary responsibilities were finance, education, and defence in the Reform Government, and he was very active in all three portfolios.
As Minister of Finance, he attempted (with only a limited degree of success) to curtail the spending of the outgoing Premier, Joseph Ward, believing strongly in the need to reduce New Zealand's overseas borrowing.
As Minister of Education, he was responsible for legislation that guaranteed statutory funding for universities.
As Minister of Defence, he encouraged New Zealand's development of naval and air capabilities independent of the United Kingdom, and worked to improve the quality of compulsory military training.
He also reversed the previous government's policy of opposing close defence co-operation with Australia.

In World War I, Allen was a major figure in New Zealand's war effort, playing a very significant organisational role.
His reforms of the military training programme were widely credited with allowing a rapid deployment of New Zealand forces, including the forces which invaded and occupied Samoa (then a territory of Germany).
In August 1915, a war-time coalition government was formed, and Allen lost his finance and education roles to members of the erstwhile Opposition, but he continued to play a significant role.
Towards the end of the war, when both Massey (the Prime Minister) and Ward (the Leader of the Opposition) travelled overseas for meetings and conferences, Allen was Acting Prime Minister - in total, he spent nearly two years in this role.
The stress of his many responsibilities during the war was considerable, and was only worsened when his son was killed in the ill-fated landing at Gallipoli.
Allen was appointed an Officer of the Legion of Honour in February 1922 when he was High Commissioner in London.
When Reform won the 1911 election, Massey became Prime Minister and Allen was elevated to Cabinet. His primary responsibilities were finance, education, and defence in the Reform Government, and he was very active in all three portfolios. As Minister of Finance, he attempted (with only a limited degree of success) to curtail the spending of the outgoing Premier, Joseph Ward, believing strongly in the need to reduce New Zealand's overseas borrowing. As Minister of Education, he was responsible for legislation that guaranteed statutory funding for universities. As Minister of Defence, he encouraged New Zealand's development of naval and air capabilities independent of the United Kingdom, and worked to improve the quality of compulsory military training. He also reversed the previous government's policy of opposing close defence co-operation with Australia.
In World War I, Allen was a major figure in New Zealand's war effort, playing a very significant organisational role. His reforms of the military training programme were widely credited with allowing a rapid deployment of New Zealand forces, including the forces which invaded and occupied Samoa (then a territory of Germany). In August 1915, a war-time coalition government was formed, and Allen lost his finance and education roles to members of the erstwhile Opposition, but he continued to play a significant role. Towards the end of the war, when both Massey (the Prime Minister) and Ward (the Leader of the Opposition) travelled overseas for meetings and conferences, Allen was Acting Prime Minister - in total, he spent nearly two years in this role. The stress of his many responsibilities during the war was considerable, and was only worsened when his son was killed in the ill-fated landing at Gallipoli. Allen was appointed an Officer of the Legion of Honour in February 1922 when he was High Commissioner in London.
James Allen (New Zealand politician)