Androgen production by the testis is essential for fetal masculinisation and male fertility. More recently androgens have been shown to support lifelong male health, with low testosterone associated with a wide range of clinical co-morbidities such as cardiovascular disease, diabetes and obesity, and also age-related degeneration. Conversely androgen replacement therapy has also been associated with negative clinical outcomes in some cases, suggesting that alternative approaches to develop, maintain, and support a healthy androgen profile throughout life are worth exploring. To address this, we have utilised a series of transgenic mouse models to dissect out genetic, cellular and age-related influences on the androgen production machinery and in particular, the testicular Leydig cells. This has identified a functional paracrine network, working through multiple cell-types, to support the development and function of this important cell type throughout life, and identified novel pathways for manipulation to improve lifelong male health.