Abstract: We report here the results of an RCT evaluating the effectiveness of a pro bono initiative’s oversubscribed divorce practice in Philadelphia County from January of 2011 until, effectively, July of 2016. The legal subject area was divorce, the quintessential example of a constitutional right that can be effectuated only by resort to the courts. Our study randomized an individual seeking assistance to pursue a divorce to either an effort by the service provider to find a pro bono attorney to represent her (treated group) or a referral to existing self-help or low bono resources coupled with an offer to answer questions by telephone (control group). Our study partner was the provider of last resort for free legal services in the Philadelphia County: it accepted intakes primarily via referrals from other organizations, and it required that service seekers exhaust all other options. Treated and control groups experienced different outcomes. If one limits one’s focus to Philadelphia County, where state venue laws “required” study participants and their opposing spouses to file, and where filing should have been most convenient for our study participants (who were all Philadelphia County residents), then we observe the following. Eighteen months after randomization, 54.1% of the treated group, as opposed to 13.9% of the control group, had a divorce case on record. Three years after randomization, 45.9% of treated group, as opposed to 8.9% of the control group, had achieved a termination of a marriage. The p-values for these differences (representing the probabilities that one would observe the numbers we observed, or numbers more extreme, if there were in fact no true difference between treated and control groups) were so low as to make them almost impossible to estimate; effectively, we observed instances of p = 0. If one expands one’s focus to other Pennsylvania counties, and thus considers filings by Philadelphia County residents who risked a dismissal due to improper venue and who abandoned the system they support as taxpayers, results remain statistically and substantively significant: 60.8% of the treated group, versus 36.3% of the control group, had a divorce case on file after 18 months, p < .00002; 50.0% of the treated group, versus 25.3% of the control group, succeeded in terminating the marriage in 36 months, p < .00002. When we account for the block randomization scheme we deployed, estimated effect sizes are a few percentage points larger than the numbers above would suggest. We conduct modeling to determine the effect of having a lawyer for divorce-seekers as a way of measuring the pro se accessibility of the divorce system. We find large effects, suggesting that the system is not accessible to pro se litigants.