| 1929 | Union with the Established Church of Scotland occurs. Carluke St John's is, once more, part of the National Church of Scotland. |
| 1932 | A replacement organ is installed. This instrument, which is still in place today, is considered to be one of the best in the county. |
| 1935 | A branch of the Women's Guild is formed in St John's. |
| | Home Communion is introduced for the elderly and sick. |
| | A monthly magazine is started, paid for by subscription through an envelope collection. |
| 1936 | Electric Lighting is installed in the church and halls, despite some objections. |
| 1939 | Extensive renovations are undertaken, including: a new pulpit, replacement choir railings and the removal of the front pews to provide more space for the choir; outside, iron railings are removed and the area in front of the door is paved. |
| 1940 | The time of the morning service is changed from 12 noon to 11.30am. 'Dress code' for elders is relaxed except for Communion and Ordination services. |
| 1941 | The time of the evening service is changed from 6pm to 6.30pm. |
| 1943 | St John's celebrates 100 years of existence. |