Left-Wing Extremism (LWE), commonly known as Naxalism or Maoism, has constituted one of India\\\'s most persistent and consequential internal security challenges since the Naxalbari uprising of 1967. At its peak in the late 2000s, the movement influenced an estimated 180 districts across a sprawling Red Corridor that bisected central and eastern India, inflicting severe losses of life, undermining state authority, and systematically impeding the delivery of public goods and development infrastructure to some of the country\\\'s most marginalised tribal and agrarian communities. The decade following the launch of the National Policy and Action Plan (NPAP) in 2015 witnessed a dramatic and statistically robust decline in both the geographic extent and operational intensity of LWE: by April 2025, affected districts had contracted to eighteen across seven states, violent incidents had declined by over 80 percent from their 2010 peak, and resultant deaths had fallen by 86 percent. This article undertakes a multi-dimensional assessment of that decline and its developmental implications for the principal affected states -- Chhattisgarh, Jharkhand, Odisha, and their neighbours. Drawing on data from the Ministry of Home Affairs, NITI Aayog, National Health Mission, and peer-reviewed scholarship, the article analyses how LWE suppression has enabled accelerated infrastructure construction, financial inclusion, educational access, and healthcare delivery, while simultaneously interrogating the structural developmental deficits that persist and that, if unaddressed, risk reconstituting the conditions for LWE resurgence. The article concludes that India\\\'s experience offers a replicable but context-dependent model in which security operations and development investment must be pursued concurrently, not sequentially, and in which the resolution of underlying structural grievances -- particularly concerning tribal land and forest rights -- remains an indispensable condition for sustainable peace.